news6.pdf - Isaac Newton Group of Telescopes

NEWSLETTER

No. 6, October 2002

T H E I S A A C N E W T O N G R O U P

O F T E L E S C O P E S

Dear Reader,

Whilst the telescopes on La Palma keep goingstrong, a large number of changes are takingshape at the ING. Last winter importantdecisions were taken by PPARC Council thathave a profound influence on the UKs ground-based astronomy programme. As a result, theUK is now a member of the European SouthernObservatory, but these decisions also imply asiginificant shift in the balance of resources.One particular implication is a reduction offunds for the ING telescopes in the future.

In order to offset the reduction of funding fromPPARC, a formal partnership with theInstituto de Astrof ísica de Canarias has beenagreed. This collaboration will furtherstrengthen international collaboration betweenthe European partners at the ORM, and at thesame time reduce the impact of the reducedUK funding.

Nevertheless, the overall reduction in resourcesenforces a number of important changes at

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Message from the Director

NAOMI Neptune in H band (1.6 microns). 120-sec integration, using as wavefront reference a star (V ∼ 10,top right) which happened to be nearby on the night. Neptunes diameter is 2.3 arcsec. The clouds areprominent in H band because of a strong methane line at a wavelength close to 1.6 micron. Triton is visiblenear the bottom of the image (see article by C. R. Benn et al. on page 21).

ING that will not go unnoticed by INGstaff or the astronomical communitythat we serve. In this Newsletter youwill read how the changes impact onthe service delivered to our usercommunity (see article on page 19).

Another significant development sincethe previous Newsletter is the creationof a new observatory advisory body.The creation of this advisory groupwith wide international participationand a wide brief, was proposed duringthe observatory review last year. I amparticularly pleased with the strongmembership of this group, and trust

that their experience will help outlinefuture directions of the observatory.

Apart from the unavoidable politicsthat surrounds the observatory, weare not losing sight of the significantastronomical results that are beingproduced. The articles based onobservations with INGRID, S-CAM,CIRSI, NAOMI and ULTRACAM providefor a number of excellent highlights.

I hope you enjoy reading thisNewsletter !

René G. M. Rutten

No. 6, October 2002 THE ING NEWSLETTER

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The ING Newsletter

ISSN 15758958 (printed version)ISSN 15759849 (electronic version)Legal License: TF1959/99

Published in Spain by THE ISAAC

NEWTON GROUP OF TELESCOPES (ING).

Apartado 321; 38700 Santa Cruz de LaPalma; Canary Islands; Spain.Telephone: +34 922 425400Fax: +34 922 425401URL: http://www.ing.iac.es/

Editorial team: J. Méndez, R. Rutten,D. Lennon and Johan Knapen.Designer: J. Méndez.Preprinting: Gráficas El Time. Tel.: +34 922 416651Printing: Gráficas Sabater. Tel.: +34 922 623555

The ING Newsletter is primarily publishedon-line at http://www.ing.iac.es/PR/newsletter/ in html and pdfformat. Notification of every newissue is given by e-mail using the[INGNEWS] mailing list. Moreinformation on [INGNEWS] can befound on page 29. Requests for one-offprinted copies can be emailed to JavierMéndez ( jma@ ing.iac.es).

The ING Newsletter is published twice ayear in March and September. If youwish to submit a contribution, pleasecontact Javier Méndez ( [email protected]).Submission deadlines are 15 July and15 January.

THE ISAAC NEWTONGROUP OF TELESCOPES

The Isaac Newton Group ofTelescopes (ING) consists of the4.2m William Herschel Telescope(WHT), the 2.5m Isaac NewtonTelescope (INT) and the 1.0mJacobus Kapteyn Telescope (JKT),and is located 2,350m above sealevel at the Roque de LosMuchachos Observatory (ORM) onthe island of La Palma, CanaryIslands, Spain. The WHT is thelargest telescope of its kind inWestern Europe.

The construction, operation, anddevelopment of the ING Telescopesis the result of a collaborationbetween the United Kingdom andthe Netherlands. The site isprovided by Spain, and in returnSpanish astronomers receive 20 percent of the observing time on thetelescopes. The operation of the siteis overseen by an InternationalScientific Committee, or ComitéCientífico Internacional (CCI).

A further 75 per cent of the observingtime is shared by the UnitedKingdom, the Netherlands and theInstituto de Astrofísica de Canarias(IAC). On the JKT the internationalcollaboration embraces astronomersfrom Ireland. The remaining 5 percent is reserved for large scientificprojects to promote internationalcollaboration between institutionsof the CCI member countries.

The ING operates the telescopes onbehalf of the Particle Physics andAstronomy Research Council(PPARC) of the United Kingdom,the Nederlandse Organisatie voorWetenschappelijk Onderzoek (NWO)of the Netherlands and the IAC inSpain. The Roque de Los MuchachosObservatory, which is the principalEuropean Northern hemisphereobservatory, is operated by the IAC.

(Continued from front cover)

The ING BoardThe ING Board oversees the operation,maintenance and development of the IsaacNewton Group of Telescopes, and fosterscollaboration between the internationalpartners. It approves annual budgets anddetermines the arrangements for theallocation of observing time on the telescopes.ING Board members are:

Prof. Janet Drew, Chairperson LondonDr. Wilfried Boland NWO, LeidenDr. Gavin Dalton OxfordDr. Ramón García López IAC, La LagunaDr. Tom Marsh SouthamptonDr. Ronald Stark NWO, The HagueProf. Thijs van der Hulst GroningenDr. Colin Vincent PPARC, SwindonDr. Simon Berry, Secretary PPARC

ING Directors Advisory GroupLast year the Isaac Newton Group of Telescopeshad its second independent internationalreview of the observatory, initiated by theING Board. The conclusions from the reviewwere very encouraging (for a summary, seethe October 2001 issue of this Newsletter).One of the recommendations of the review wasthat ING should set up a Director s AdvisoryGroup. Such a group would assist theobservatory in defining the strategic directionfor operation and development of thetelescopes. It would also provide aninternational perspective and act as anindependent contact point for the communityto present its ideas. This new group replacesthe instrumentation Working Group thatfulfilled part of this function to date.

Dr Mark McCaughrean (Potsdam) has kindlyagreed to chair this new advisory committee.Further members are: Thijs van der Hulst(Groningen), Ramón García López (IAC, LaLaguna), Phil James (Liverpool) and NialTanvir (Hertfordshire).

We describe results from ourstudy of a sample of spiralgalaxies of a wide range of

Hubble types on the basis of near-IRimaging obtained with INGRID onthe WHT. We focus on thedetermination of bar torques, or barstrengths, from our images, and showthat this bar strength only veryweakly correlates with de Vaucouleursbar type, or with bar axis ratio.

1. INGRID on the WHT

INGRID, the near-IR (NIR) camerafor the WHT, has been in routineoperation at the Cassegrain focus foralmost two years now. In the threesemesters from August 2000 untilJanuary 2002, it has been inscheduled use for 37, 35, and 35 nights( including NAOMI science runs,excluding commissioning and service),or 20% of the time. This makes INGRIDthe second-most used instrument onthe WHT, after ISIS. The scientificareas that have been attacked withINGRID span an enormous range, fromobservational cosmology to browndwarfs and giant planets. INGRIDsmain attraction is the relatively largefield-of-view, of just over 4 arcmin,coupled with a pixel size of 0.24 arcsecwhich samples all except the very bestseeing conditions. Here, we present

results obtained from a number ofPATT-supported observing runs, aimedat imaging nearby and relativelyface-on spiral galaxies.

2. Barred Galaxies

One of the main attractions of observingin the NIR is that one is much lesssusceptible to the attenuation ofemission by dust. Compared to thevisual (V-band), extinction by dust isa full order of magnitude less in theNIR K-band, at 2.2 microns. Since atrest wavelength (i.e., in nearbygalaxies) the NIR light also traces arelatively old stellar population, NIRimaging is the technique of choice toobserve the stellar backbone ofgalaxies: the old stellar populationwhich, by assumption of a mass-to-light (M/L) ratio, will give an estimateof the mass. We imaged a completesample of 57 galaxies with INGRIDfor this reason: to study the old stellarcomponent, not affected by dustextinction. In one of the lines of ouroverall project, the INGRID Ks imagingwill be compared with B and R broad-band images, as well as with narrow-band Hα images which trace young,massive stars and current starformation. This comparison canindicate how mass and star formationare concentrated in spiral arms, and

why they are concentrated to adifferent degree.

In this short article, though, we willfocus on bars in galaxies. About 75%of all disk galaxies have bars (Sellwood& Wilkinson, 1993; Knapen, 1999),where stars move on elongatedperiodic orbits and thus support anon-axisymmetric potential. Gas inbars shocks and loses angularmomentum, which implies that barsform a mechanism to transportmaterial inward in a rotationallysupported galactic disk. This explainswhy bars are relevant for questionsrelated to the origin, evolution, andmaintenance of stellar and non-stellaractivity in or around the nuclei ofgalaxies: massive black holes, AGN or(circum)nuclear starbursts all needfuel to maintain their activity andwhereas enough gas is available in thedisk at large, moving this gas inwardsimplies making it lose a considerableamount of angular momentum.

NIR imaging is the best way of findingand classifying bars. At opticalwavelengths, the bar may be maskedby the combined effects of emissionfrom young stars, and extinction bydust. There are a number of well-known and spectacular examples ofbars which are unrecognisable in thevisible, but well-defined in the NIR

THE ING NEWSLETTER No. 6, October 2002

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INGRID: Early Science Results

Bar Strengths in Galaxies as Measured fromINGRID Images

J. H. Knapen1, D. L. Block2, R. Buta3, I. Puerari4, B. G. Elmegreen5, S. Stedman6, D. M. Elmegreen7

1: ING and University of Hertfordshire; 2: University of the Witwatersrand; 3: University of Alabama; 4: INAOE; 5: IBM; 6: University ofHertfordshire; 7: Vassar College

The INGs Red Imaging Device (INGRID) saw first light on the William Herschel Telescope inMarch 2000. In over 2 years of operation the instrument has proven to be a highly efficient

infrared imager. Below we present four articles with science results from INGRID data.

(e.g., Block & Wainscoat, 1991; Blocket al., 1994). However, statisticalstudies (e.g., Mulchaey & Regan,1997; Knapen, Shlosman & Peletier,2000; Eskridge et al., 2000) haveshown that the overall bar fractiononly goes up by 1015% in the NIRas compared to classification fromoptical imaging. Still, the NIR is muchpreferred for any detailed and/orquantitative studies of bars, becausethe bar parameters can be measuredmuch more cleanly there than inthe optical.

3. Determining BarStrength

Of the main structural parameters ofbars: length, axis ratio, luminositydistribution, and strength, the latterhas proved to be by far the mostelusive observationally. Theoretically,bar strength can be defined rathereasily as some measure of the ratio ofnon-axisymmetric, or tangential, overaxisymmetric gravitational force.Observationally, bar strength hasoften been measured as bar ellipticity,or axis ratio, but this is strictlyspeaking incorrect. This is easy toillustrate by imagining a very ellipticalbar in a galaxy which also has amassive bulge. In that case, the netgravitational pull felt by a particle (beit gaseous or stellar) in the bar willbe that caused by the bar, but offsetsignificantly by the axisymmetricgravitational pull of the bulge. Thus,the net bar strength in that case can

be much less than in the case of aless elliptical bar in a bulge-less galaxy.

A quantitative observational measureof bar strength has recently beendeveloped by Buta & Block (2001),based on an old of idea of Combes &Sanders (1981). Buta & Block calculatethe maximum, Qb , of the ratio of thetangential force to the meanaxisymmetric radial force. Technically,this is done by a Fourier analysis ofdeprojected images, under theassumption of a constant mass-to-light ratio. This means that theobservational input data must be NIRimages with a high signal-to-noiseratio, which in turn implies apreference for bright, thus nearby,galaxies. This is where INGRID isideal: the 4.2-m WHT mirror ensuresa high S/N ratio, whereas the field ofview of 4.2 arcmin facilitates theimaging of disks of nearby galaxies. Wethus derived bar strengths, Qb , forthose galaxies in our sample of 57galaxies where this could be determined(45 of them, the images of the othersare not of high enough S/N ratio).

The galaxies in our sample wereselected to have an angular diameterof more than 4.2 arcmin and aninclination of less than 50 degrees. Oursample covers the complete range inHubble type for spiral galaxies, as wellas in Elmegreen spiral arm class(Elmegreen & Elmegreen, 1987), fromflocculent to grand-design. As anexample, we show, in Figure 1, V andKs-band images of the SA(rs)b galaxy

Messier 88 (NGC 4501), where theV-band image was obtained with INGs1-m JKT. This Ks-band image is oneof our deepest, with a total on-sourceintegration time of over one hour. TheVKs colour index image clearly showsthe location of the star-forming spiralarms (as lighter shades) and the dustlanes which accompany them (darker).

4. Results

In Figure 2 we show nine of our samplegalaxies, ranked in terms of increasingbar strength or torque. The locationswhere the ratio of the tangential forceto the mean axisymmetric radial forcereaches a maximum are indicated ineach galaxy image by four filled blackor yellow dots. Figure 3 shows amontage of Ks images of 9 two-armedspiral galaxies in our sample, rankedvertically in terms of bar torque, andhorizontally in terms of pitch angleclass, where class a contains the mosttightly wound spirals.

Combining our results on the barstrength Qb with those obtained byButa & Block (2001) for 30 galaxies,we now have a sample of 75 galaxieswith bar strengths determined fromNIR imaging. In Figure 4, we plot thebar strength Qb against the deprojectedbar axis ratio, often used as a barstrength indicator, for those galaxieswhere the latter number has beenpublished by Martin (1995). Whereasthere is a general trend, as expected,where the most elongated bars (high


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Figure 1. V, Ks, and VKs colour index images of the SA(rs)b galaxy Messier 88 (NGC 4501), as obtained with INGRID onthe WHT and with the JKT. The field of view of the images is ~7 arcmin, but only the central 4 arcmin is shown here.

ellipticity or axis ratio) also have thehighest bar torques or strengths, thespread in Qb for each axis ratio is verylarge, and in fact large enough as toinvalidate any claims that barellipticity is a reliable bar strengthestimator. For example, bars withmoderate ellipticity (axis ratios of0.4 0.5) span the entire range of barstrengths Qb and their ellipticitiesare thus completely useless todiscriminate strong from weak bars.It is only at the very extreme ends ofthe bar axis ratio range that such adiscrimination might have a chanceof success. Laurikainen, Salo &Rautiainen (2002) derive Qb using aslightly different method, and comparetheir values with bar ellipticities.They find a better correlation betweenQb and bar axis ratio than we do,possibly due to the fact that the latterwere derived from NIR images,whereas Martin (1995) used bluelight photographs.

In Figure 5, we plot Qb for each galaxyagainst its classification from deVaucouleurs (1963), who classifiedgalaxies as un-barred (SA), barred (SB)or intermediate (SAB, often referredto as weakly barred though this maynot be correct in all cases). A cleartrend is seen where the SB galaxieshave higher bar strengths Qb than SAor SAB galaxies, but more interestingis the considerable overlap in Qb valuesbetween the SA, SAB and SB classes.This implies that many of the galaxiesclassed as SAB in fact have strongerbars than many classed SB, and eventhat a considerable number of SABgalaxies have weaker bars than othersclassed as un-barred ! In addition,Figure 5 shows clearly that the effectof overlapping bar strength is not dueto either early- or late-type galaxies,but is present equally for all sub-types.Massive bulges, which will dilute barstrength, are thus not the cause of theobserved effect. Apparently, the relativebar strength comes from a complexmixture of bar amplitude, radialprofile and relative length, combinedwith the bulge strength. The resultingspread of Qb for each Hubble subtypeis due to the different ways in whichthese quantities vary along the Hubblesequence. How exactly this affects


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Figure 2. Deprojected Ks images of nine galaxies observed with the 4.2-m WHT,ranked in terms of increasing bar strength, or torque. The four filled black oryellow dots indicate the locations where the ratio of the tangential force to themean axisymmetric radial force reaches a maximum. From Block et al. (2001).

Figure 3. Montage of 9 Ks images of two-armed spirals, which have been rankedvertically in terms of bar torque, where the strongest bars are seen in the lowerpanels, and horizontally in terms of pitch angle class, where class α containsthe most tightly wound spirals. From Block et al. (2001).

the bar parameters, and the influencethe bar has on its surroundings, isnot clear, and is the subject of ourfurther exploration, partly aided byINGRID imaging.

5. Summary

In this short paper, we illustrate thepower of the INGRID NIR camera onthe WHT in obtaining deep, wide-field,imaging of nearby spiral galaxies. Wedescribe results from our study of bartorques, or bar strengths, in a largesample of galaxies which we imagedwith INGRID, and show that this barstrengths only very weakly correlateswith de Vaucouleurs bar type, or withbar axis ratio.

References:

Block, D. L. & Wainscoat, R. J., 1991,Nature, 353, 48.

Block, D. L., Bertin, G., Stockton, A.,Grosbol, P., Moorwood, A. F. M.,Peletier, R. F., 1994, A&A, 288, 365.

Block, D. L., Puerari, I., Knapen, J. H.,Elmegreen, D. M., Buta, R., Stedman,S., Elmegreen, D. M., 2001, A&A, 375,361.

Buta, R. & Block, D. L., 2001, ApJ, 550,243.

Combes, F. & Sanders, R. H., 1981, A&A,96, 164.

de Vaucouleurs, G., 1963, ApJS, 8, 31.

Elmegreen, D. M. & Elmegreen, B. G.,1987, ApJ, 314, 3.

Eskridge, P. B. et al., 2000, AJ, 119, 536.

Knapen, J. H., 1999, in The Evolution ofGalaxies on Cosmological Timescales,J. E. Beckman & T. J. Mahoney, Eds.,ASP Conf. Ser., 187, 72.

Knapen, J. H., Shlosman, I. & Peletier,R. F., 2000, ApJ, 529, 93.

Laurikainen, E., Salo, H. & Rautiainen, P.,2002, MNRAS, in press (astro-ph/0111376).

Martin, P., 1995, AJ, 109, 2428.

Mulchaey, J. S., & Regan, M. W., 1997,ApJ, 482, L135.

Sellwood, J. A. & Wilkinson, A., 1993,

Rep. Prog. Phys., 56, 173. ¤

Johan Knapen ([email protected])

rates (e.g. SN 1998S, Fassia et al.,2000). However, the behaviour of SNein nuclear starburst regions may bemuch more extreme (Terlevich et al.,1992). The high-z CCSN surveys withthe VLT, HST and NGST (e.g.,Dahlen & Fransson, 1999; Sullivanet al., 2000) will use SNe to probe thecosmic star formation rate. For this, itis important to determine (i) a betterestimate of the complete local CCSNrate (cf. Sullivan et al., 2000), (ii) aproper understanding of the behaviourof SNe within the dusty, high-densitystarburst environment and (iii) theextinction towards these events.

Most of the CCSNe in young starburstslike M 82 (Figure 1; Mattila & Meikle,2001, 2002) are expected to be heavilyobscured by dust, and therefore remainundiscovered by current SN searchprogrammes working at opticalwavelengths. However, in the near-IRKs-band the extinction is greatlyreduced and the sensitivity ofground-based observations is still good.That is why we are using INGRID tocarry out an imaging survey of the

W e are currently carrying outa Ks band survey for core-collapse supernovae (CCSNe)

in the nuclear (central kpc) regions ofnearby starburst galaxies with theINGRID near-IR camera at the WHT.In this article we concentrate ondescribing mainly the observations andthe real time processing of the SNsearch data, which makes use of theINGs integrated data flow system.

Very little is currently known aboutthe behaviour of SNe in a starburstenvironment. The enhanced metallicityin starburst regions is expected toresult in large mass-loss rates (Vinket al., 2001) for the SN progenitorstars. In addition, many of these eventsare expected to occur within molecularclouds (Chevalier & Fransson, 2001),adding further to the density ofmaterial surrounding the SN.Therefore, nuclear SNe can be expectedto explode within a dense circumstellarmedium. In general, a dense (butnon-nuclear) circumstellar environmenthas been observed to produce brightCCSNe with slow near-IR light decline


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Figure 4 (left). Bar strength plotted as a function of deprojected bar ellipticity, or baraxis ratio. From Block et al. (2001). Figure 5 (right). Bar strength plotted as a functionof Hubble type for our sample galaxies. From Block et al. (2001).

Searching for Obscured Supernovae inNearby Starburst Galaxies

Seppo Mattila (Imperial College), Robert Greimel (ING), PeterMeikle (Imperial College), Nicholas A. Walton (IoA), StuartRyder (AAO), Robert D. Joseph (IfA)

∼ 40 most luminous nearby (d < 45 Mpc)starburst galaxies visible in thenorthern hemisphere. These galaxieshave been selected to have far-IRluminosities greater than orcomparable to those of the twoprototypical starbursts, M 82 andNGC 253, but excluding galaxies whosefar-IR luminosity is powered by apopulation of old stars or an AGN. Theexpected CCSN rates in these galaxies(Mattila & Meikle, 2001) range from

around 0.05 yr 1 in NGC 253

(LFIR ~ 1010.3 L and 0.2 yr 1 in

NGC 4038/39 (LFIR ~ 1010.8L ) to


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O.Figure 1. Extinctions (AV) towards 33SNRs in M 82 (from Mattila & Meikle,2001, 2002).

Figure 2. Ks band images of Apr 299 (North is up and East to the left) obtained with INGRID at the WHT on January 2nd, 2002.Four quadrant jitter frames with 10×6 sec. exposure time are shown on the left, and the combined frame formed from 32 individualframes (32 minutes total exposure time) on the right. The intensity in the combined frame has a square root scaling.

around 1 2 CCSNe per year inArp 299 (LFIR ~1011.8L ).

Since the average distance to ourtargets is ∼ 30 Mpc, most of them fitwell within one quadrant of theINGRID detector (2 arcmin×2 arcmin).This enables us to observe most of thetarget galaxies using the quadrantjitter method in which the galaxynucleus is placed in the middle ofeach quadrant of the array in turn.As the three other quadrants containempty sky, the actual target framescan be used to create a sky frame foreach of the galaxies and a sky flatfield frame for the whole night. Thus,

there is generally no need for offsetsky images. This improves theobserving efficiency allowing 2 3galaxies to be observed per hour (with10 20 minutes on-source exposuretime each). The catch of a clear nightis therefore 20 30 galaxy images inwhich nuclear CCSNe might be hiding.In Figure 2 we show four individualframes and the final combined frameof Arp 299, a luminous infrared galaxyat a distance of 45 Mpc, as an exampleof a quadrant jitter observation. InFigure 3 the Ks image of anothersample galaxy is shown, NGC 4038/39(the Antennae, distance 20Mpc). Ingeneral, to increase the number offrames and thus the total on-sourceexposure time per galaxy we performa 4-point dither on each of thequadrants in turn. Therefore, a fullquadrant jittering cycle producestypically 16 frames per galaxy, all withdifferent offsets. When creating a skyframe the quadrants in which thegalaxy is known to be are masked out.Thus the number of pixels which aremedian-combined to form a sky frameis 12. The observing procedure is

Figure 3. Ks band image of the Antennae,NGC 4038/39 (North is up and East tothe left) obtained with INGRID at theWHT on January 2nd, 2002 (640 secondexposure time).

O.

O.

simplified by the use of scripts whichcontrol the telescope/data acquisitionsequence. The target quadrantidentification is encoded into the objectstring in the image header, forsubsequent use by the data pipeline.

The full sampling of the seeing disk(FWHM ∼ 0.7'') by INGRID (0.24''/pixel)allows us to compare the reducedgalaxy images to reference framesobtained earlier, using imagesubtraction. For this we use theOptimal Image Subtraction method(Alard & Lupton, 1998; Alard, 2000)which derives a convolution kernel tomatch the better seeing image to theimage with the poorer seeing. It alsomatches the background differences.In Figure 4 we show an example ofimage subtraction using a pair ofimages of NGC 253 (distance ∼ 3 Mpc)observed under different seeing andphotometric conditions in August 2001(FWHM = 0.9'') and January 2002(FWHM = 1.1''). Here, 21 different5.7''× 5.7'' regions automaticallyselected by the image subtractionprogram were used for deriving the

convolution kernel. The spatialvariations of the INGRID PSF weremodelled with a 2nd order polynomialand the differential backgroundvariations with a 1st order polynomial.The subtraction residuals are verysmall except for the two bright starsvisible in the north-east and south-westfrom the nucleus. When the imagesubtraction is carried out with aconstant kernel solution using just one

de-dithering routine (idedither_qd)from the INGRID quicklook package(ingrid_ql) in which the images areregistered on a user defined star (thiswill be automated in future); a finalsky image is created based onquadrant masking; then every image issky subtracted, bad pixel masked andflat fielded; and the processed imagesare finally combined. The lastprocessing step is to apply a WorldCoordinate System (WCS) solutionbased on the USNO catalogue to thecombined image. At this point a dataanalysis task takes over. The newimage of the object is compared withan archived image from previous runs.The rotation, shift and scaling arecalculated for the image, based onuser-selected stars. In the future thiswill be automatically done based onthe WCS solution. The final step inthe data analysis is the imagesubtraction using the Optimal Imagesubtraction software (ISIS) as describedabove. The subtracted images are theninspected by eye. In addition, the fullyreduced search images are comparedto the existing reference images byblinking. Apart from automating thevarious pipeline steps, we are alsoworking on the implementation of aweb-based interface for the pipelinewhich will allow easy steering of thepipeline as well as immediate accessto the data by off-site collaborators. Having acquired a complete set ofINGRID reference images we estimatea probable discovery rate of between

0.4 and 0.8 SNe in each clear night sobservations (see Mattila & Meikle,2001, 2002). The newly developed dataprocessing pipeline for the on-goingnuclear CCSN search on the WHTenables an easy real-time analysis ofthe search data. This is essential forthe rapid follow-up observations ofdiscovered SNe, in order to determinethe nature of these events. Near-IR(JHK ) photometry and spectra willprobe both the conditions in theimmediate circumstellar/interstellarenvironment of the SN and the line-of-sight extinction towards the SN.A large amount of near-IR imagingdata still needs to be collected if weare to detect a sufficient number ofobscured SNe to derive a statisticallysignificant SN rate in nearby starburstgalaxies. Therefore, we invite anyobservers who will be acquiring orhave recently acquired K-band data ofluminous nearby starburst galaxies totake part in the Nuclear SN search.Full details of this, and contactinformation, are given on the NuclearSN Search pages athttp://astro.ic.ac.uk/nSN.html

We thank Johan Knapen and PetriVäisänen for advice and discussionson the observing technique. ¤

References:

Alard C., Lupton R. H., 1998, ApJ, 503, 325.

Alard C., 2000, A&AS, 144, 363.

Chevalier R. A. & Fransson C., 2001, ApJ,558, 27.

Dahlen T. & Fransson C., 1999, A&A,350, 349.

Fassia A. et al., 2000, MNRAS, 318, 1093.

Greimel R., Lewis J. R., Walton N. A.,2001, ING Newsl, 4, 9.

Mattila S., Meikle W. P. S., 2001, MNRAS,324, 325.

Mattila S., Meikle W. P. S., 2002, in Thecentral kpc of starbursts and AGN: theLa Palma connection, eds. J. H. Knapen,J. E. Beckman, I. Shlosman and T. J.Mahoney, ASP Conf. Ser., 249, 569.

Terlevich R., Tenorio-Tagle G., Franco J.,Melnick J., 1992, MNRAS, 255, 713.

Sullivan M., Ellis R., Nugent P., Smail I.,Madau P., 2000, MNRAS, 319, 549.

Vink J., de Koter A., Lamers H. J. G. L.M., 2001, A&A, 369, 574.

Seppo Mattila ([email protected])


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region centred on the galaxy nucleusfor deriving the kernel, a slight PSFvariation between the frames over theINGRID field of view (4 arcmin×4 arcmin) is visible. Such relative PSFvariations can be caused by e.g.differential rotation between the twoframes (Alard, 2000) as a result ofimperfect image registration. Moreimage subtraction examples andstarburst galaxy images can be foundat http://astro.ic.ac.uk/nSN.html.

The quick, effective reduction andanalysis of the SN search data isessential for this programme tosucceed. Therefore, the INGRID datataken in this project are pipeline-processed in near-real time at thetelescope (see Figure 5). The IRAF-based pipeline runs on one of theBeowulf clusters at the telescope(Greimel et al., 2001). At the beginningof the observing run, calibration datais taken to generate a bad pixel maskand a dome flat field for the imageprocessing. When a new image is takenby the Data Acquisition System it isautomatically copied to the clusterand the post-pre image subtraction isdone. An image grouping task thenwaits until all the exposures for agiven galaxy have been taken beforefeeding the list of exposures to thenext step. Once all the images for oneobject are on the cluster they arecombined to give an initial sky frame.The images and the initial sky frameare then fed into a modified

Figure 4. Ks band image of NGC 253 (North is up and East to the left) obtained withINGRID at the WHT on August 31st, 2001 (300 second exposure time) is shown witha square root intensity scaling on the left. The result of image matching and subtractionis shown on the right.

necessity of a multi-wavelengthapproach to studies of galaxy evolutionat z 1. Thus a range of surveysspanning wavebands from the X-ray,near- and mid-infrared, submillimeterand out to the radio, havecomplimented the traditional viewbased on UV/optical observations.These new studies have all tended tostress the role of dust obscuration incensuring our view of the galaxypopulation at high redshifts, andespecially in disguising the extent ofactivity in the most activeenvironments, both AGN and star-forming systems. This is much moreof a concern due to the very strongevolution seen in obscured populations,which result in them dominating the


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Figure 5. The real-time data analysis pipeline.

The INGRID MDS ERO Survey

David Gilbank (University of Durham), Ian Smail (University of Durham), Rob Ivison(Astronomy Technology Centre), Chris Packham (University of Florida), Richard Bower(University of Durham)

W e are taking advantage ofthe wide-field near-infraredimaging capabilities of

INGRID on the WHT to construct adeep, wide area survey for ExtremelyRed Objects (EROs) in archival HubbleSpace Telescope Medium Deep Survey(MDS) fields.

The last five years have seen a growingappreciation of the diversity of galaxyproperties at z 1 2. In part this hascome about from an impressive growthin our observational knowledge ofgalaxies at these redshifts driven bythe availability of powerful newinstruments on 4- and 8-m classtelescopes. However, an equal role hasbeen played by the realisation of the

>∼

bolometric emission at high redshifts(e.g. Haarsma et al., 2000; Smailet al., 2002).

One of the most striking themes toarise from this new multi-wavelengthview of galaxy formation is the ubiquityof optically-faint, but bright near-infrared counterparts to sourcesidentified in many wavebands: in theX-ray (Cowie et al., 2001; Page et al.,2001), the mid-infrared (Pierre et al.,2001; Smith et al., 2001), submillimeter(Smail et al., 1999; Lutz et al., 2001)and radio (Richards, 1999; Chapmanet al., 2002). This has resulted in arenaissance in interest in suchExtremely Red Objects a class ofgalaxies which had previously been

>∼

viewed as a curiosity with littlerelevance to our understanding ofgalaxy formation and evolution comprising a mere 5 10 % of thepopulation down to K =20.

The ERO class is photometrically-defined one frequently useddefinition is I K ≥ 4 (or a more extremeselection of I K ≥ 5). This very redoptical-near-infrared colour is intendedto effectively isolate two broadpopulations of galaxies at z 1: thosewhich are red by virtue of the presenceof large amounts of dust (resultingfrom active star formation), as well aspassive systems whose red coloursarise from the dominance of old,evolved stars in their stellarpopulations. The very different natureof these two sub-classes, dustystarbursts and evolved ellipticals, hasprompted efforts to disentangle theirrelative proportions (Pozzetti &Mannucci, 2000) so that well-definedsamples can be used to test galaxyformation models (Daddi et al., 2000;Smith et al., 2002; Firth et al., 2002).

One particularly powerful approach isto use the morphology of the ERO to


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Figure 1 (left). Preliminary IK, K colour-magnitude diagram from 85 sq. arcmins ofdata from our survey. These data cover 17 HST WFPC2 fields with typical integrationtimes of 6.0ks in the I (F814W) passband and 3.0ks in the K-band with INGRID. TheINGRID data for this survey was taken in typically good conditions, 0.50.9'' FWHM, whilethe HST imaging has nominally 0.1'' resolution, although poor signal to noise for thereddest galaxies targeted here, I-K 45. We catalogue a total of 55 galaxies brighterthan K=20 and redder than IK=4, of which 7 are redder than IK=5. The equivalentsample for the full survey will have around 170 and 20 respectively. Figure 2 (right).A true colour I/Ks image of one of our fields. An extreme ERO, IK>5, is visibleto the south-east of the brightest star. Other (IK>4) EROs are indicated by arrows.Theunusual shape of the image arises from the coverage of the WFPC2 image. Thefield is ∼ 4' in diameter meaning that the WFPC2 field is completely covered byINGRID, irrespective of the roll angle of HST when the observations were taken.The image reaches 5σ point source sensitivities of K∼ 20 and I∼ 26.

>∼

distinguish regular, relaxed ellipticalsfrom disturbed and dusty starbursts.

A common misconception is that thekey to a successful ERO survey is toobtain deep NIR imaging in fact,the observationally most demandingaspect is achieving the necessarydepth in the optical to identify that agalaxy is an ERO. For this reason, wehave chosen to concentrate our surveyon fields for which deep, high-qualityarchival optical imaging already exists.These fields come from the MediumDeep Survey (Griffiths et al., 1994)who have amassed over 500 deepHST/WFPC2 images of intermediate/high-Galactic latitude blank fields.These represent high-resolution (0.1'')and very deep (I ∼ 27) images of randomareas of extragalactic sky. Using asample taken from the 100 deepest I-band MDS fields (covering an effectivearea of 500 sq. arcmin) we are able toobtain morphological information(sufficient to distinguish compact,regular evolved early-type galaxiesfrom the more distorted starbursts)for galaxies as faint as I=25. Six nightsof INGRID time in November 2000and a further six in May 2001 have

resulted in over 50 MDS fields beingimaged in Ks and more than 30 ofthese also in J, to 5σ limitingmagnitudes of Ks= 20 and J =22.5. Itis thanks to the generous field of viewof INGRID that such a survey ispossible in a reasonable amount oftelescope time. In contrast UFTI onUKIRT would take a factor of 3 4longer to tile each MDS field. Thesedata will form the basis of a sampleof EROs with which we can undertakeNIR spectroscopy on 8-m classtelescopes, selected from an area anorder of magnitude larger than theCimatti et al. (2000) survey.

Preliminary results are shown inFigure 1. From 85 square arcmins,55 EROs are found with IK ≥ 4 and7 with IK ≥ 5. The samples from thefull survey of 260 sq. arcmin will be170 and 20 respectively. A colourimage of one field made from INGRIDdata is illustrated in Figure 2. Thissurvey is supported by the LeverhulmeTrust. ¤

References:

Chapman, S. C., Lewis, G. F., Scott, D., Borys,C., Richards, E., 2002, ApJ, 570, 557.

Cimatti, A., Villani, D., Pozzetti, L., di SeregoAlighieri, S., 2000, MNRAS, 318, 453.

Cowie, L. L., et al., 2001, ApJ, 551, L9.

Daddi, E., Cimatti, A., Renzini,A., 2000,A&A, 362, L45.

Firth, A. E., et al., 2002, MNRAS, 332, 617.

Griffiths, R. E., et al., 1994, ApJ, 435, L19.

Haarsma, D. B., Partridge, R. B., Windhorst,R. A., Richards, E. A., 2002, ApJ, 544, 641.

Lutz, D., et al., 2001, A&A, 378, 70.

Page, M. J., Mittaz, J. P. D., Carrera, F.J., 2001, MNRAS, 325, 575.

Pierre, M., et al., 2001, A&A, 372, L45.

Pozzetti, L., Mannucci, F., 2000, MNRAS,317, L17.

Richards, E. A., 1999, ApJ, 513, L9.

Smail, I., et al., 1999, MNRAS, 308, 1061.

Smail, I., Ivison, R. J., Blain, A. W.,Kneib, J.-P., 2002, MNRAS, 331, 495.

Smith, G. P., et al., 2001, ApJ, 562, 635.

Smith, G. P., Smail, I., Kneib, J.-P.,Davis, C. J., Takamiya, M., Ebling, H.,Czoske, O., 2002, MNRAS, 333, L16.

David Gilbank ([email protected])

>∼

T owards the end of the lastdecade, the internationalastronomical community

realised that exploitation of the newgeneration of 8 10-m class telescopeswould be hampered unless surveys ofthe sky with suitable depth werecarried out. Spurred by this realisation,several observatories and researchgroups planned and established surveyprograms. Examples are theNOAO Deep Wide-Field Survey(http://www.noao.edu/noao/noaodeep/),the ING Wide Field Imaging Survey(http://www.ing.iac.es/WFS/),the DEEP project(http://deep.ucolick.org/), the CADIS survey (http://www.mpia-hd.de/GALAXIES/CADIS/science_index.html) and manyothers. Deep surveys aimed at thestudy of distant galaxies require NIRimaging in order to cope with thecosmological redshift of the galaxyspectral energy distributions (SEDs). In2000 our group started a deep surveyin the Ks-band using INGRID on theWHT and Omega Prime on the CAHA3.5-m telescope. Our goal is to cover0.5 square degrees of high-galacticlatitude sky. Our target depth isKs= 22 in AB magnitudes. Good LaPalma seeing and better noisebehaviour allows us to reach this depthin 2 hr exposures with INGRID, theCAHA/Omega data being about 1 mag.shallower for equal exposure times.On the other hand, the wider field ofOmega allows a faster coverage of skyarea. Our survey, deemed the COSMOSSurvey, thus has two depth regimes,KAB= 21 on a wide area and KAB= 22on the deeper areas mapped withINGRID. This depth allows us to mapluminous blue compact galaxies(LBCGs) with MB= 21.4 out to z = 2.4(H0= 70) (Cristóbal et al., 2000).

Foremost in the science motivation forthe COSMOS survey is to produce a

database of distant galaxies for studywith EMIR, the NIR multi-objectspectrograph now in construction forthe upcoming 10-m GTC on the ORM.EMIR is described in Balcells (1999and 2000). Up-to-date information onthe instrument is posted athttp://www.ucm.es/info/emir/.Operating at cryogenic temperatures,EMIR will be one of the firstspectrographs capable of performingmulti-object spectroscopy in the2.2-µm K-band. EMIR will allow usto efficiently obtain rest-frame visiblespectra of large samples of galaxiesat redshifts above 2, thus allowingthe analysis of all the emission linesthat have traditionally provided uswith diagnostics on the excitation,extinction, star formation rates,metallicities, etc. of nearby galaxies.

Because of the (1+ z)4 cosmologicalsurface brightness dimming, high-zsources in the COSMOS survey willpredominantly be luminous, compact,i.e. high surface brightness galaxies.Best known among these are star-forming galaxies for the ease withwhich they can be identified viaU-band dropout and related techniques(Steidel et al., 1996). Such galaxies atz ∼ 2 will remain keys to understandingthe rate of cosmic star formation whenEMIR comes into operation. Of specialinterest is the possible connection ofLBGs and other z = 3 compact galaxies(Lowenthal et al., 1997) to luminousblue compact galaxies (LBCGs) foundat 0.5 < z < 1 (Guzmán et al., 1997). TheCOSMOS survey should also breakground in cataloguing galaxies withoutthe strong star formation rates ofLyman-break galaxies. At 2 < z < 3,current surveys, selected in the visible,sample the UV continuum and arebiased toward actively star-forminggalaxies. COSMOS is mapping rest-frame R, which is sensitive not only toluminous star-forming galaxies but

also to luminous, massive galaxiesharbouring old populations.

For galaxy selection, photometricredshifts and photometriccharacterisation of the sources weplan to use complementary data atvisible wavelengths, which we aregathering via our own parallel surveysand via collaborative agreements withother groups.

Survey fields were selected for theirhigh-galactic latitude, low cirrusemission, lack of bright stars, andperhaps most importantly for theavailability of complementary datafrom HST and at other wavelengths.Our fields now include: the Groth field,including a strip of 28 deep, two-band,HST/WFPC2 pointings and itsflanking fields; the Coppi field,containing a deep exposure with theChandra X-ray satellite; one of theSIRTF First-Look Survey fields, andthe Koo-Kron SA68 field. COSMOSwill also observe equatorial fieldssuch as the NOAO Deep Survey 2-hrfield, to make use of existing publicmulti-band databases, and to allowspectroscopic studies with VLT andGemini-S in addition to the GTC.

To date, data was obtained on runsin April 2000, October 2000 and June2001. Our first run was part of thefirst science run of INGRID, soon afterthe camera commissioning. We arepleased to acknowledge a lack oftechnical problems, a smooth cameraoperation, and the high cosmeticquality of the images not to mentionthe 0.7" FWHM seeing we obtainedin the first 2-hr coadded images. Wewere then operating with thetemporary collimator which gavereduced throughput, and, in theexcellent seeing, gave a slightlynon-circular PSF. These problemsdisappeared in 2001 using thedefinitive INGRID collimator. We


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The COSMOS NIR Survey with INGRID

Marc Balcells, David Cristóbal-Hornillos, Mercedes Prieto (Instituto de Astrofísica de Canarias),Rafael Guzmán (University of Florida), Jesús Gallego, Angel Serrano, Nicolás Cardiel(Universidad Complutense de Madrid), Roser Pelló (Obervatoire Midi-Pyrenées)

were pleased by the ease with whichthe camera operation could beprogrammed using UNIX scripts,allowing us to prepare custom-madedithering patterns tailored to thegeometry of our fields, or to readilyprogram and execute long linearitycalibration exposure sets. We note asingle technical problem, which waseventually clarified with the ING staff:an inaccuracy (an offset of a fractionof a second) in the exposure timesrecorded in the headers during thefirst months of operation.

Data reduction for the Survey wascarried out using IRAF. For skysubtraction, we found the dimsumtask (Stanford, Eisenhard & Dickinson,1998) particularly adequate. Ourpipeline, while not fully automated,allows now for streamlined reductionof long observing runs, reaching flat-field accuracies of 6×105 (peak-to-peak in the uniformly exposed areas).Our photometric calibration accuracy,in good atmospheric conditions, istypically 0.03 mag.

With INGRID, we have mapped theGroth strip, the Coppi field and afraction of the SA68 field, for a totalof 303 arcmin2. Figure 1 shows asample image from the Groth strip,together with the same field imagedin F606W with HST. The HST Grothimages were obtained from the HSTarchive. We have performed sourcecount and photometry using SExtractor(Bertin & Arnouts, 1996). Essentialfor deep galaxy photometry is toobtain reliable estimates of detectionefficiency and spurious fraction(detection reliability). For the latter,we have developed a test, inspired onthat used by Bershady et al. (1998),which we found more robust thantests based on injecting syntheticsources from eg. artdata.mkobjectin IRAF. Our test relies on comparingphotometry performed on two disjointsets of co-added frames, eachcorresponding to half the totalexposure time. Good detection of agiven source in the two half-timeimages provides reliability that thesource is real. A spurious source, incontrast, must come from a noisepeak and therefore be detected onone of the two half-time images only.

With this assumption, we deemspurious any detection in which thephotometry in any one of the twohalf-time images is below a givenSNlim. To determine the value of SNlimthat isolates truly spurious sources,we construct the histogram ofmagnitude differences between themeasurements in the two half images.Values of SNlim that isolate spurioussources lead to a double-peakedhistogram of magnitude differences,while values which do not, i.e. whichinclude real sources, yield a histogramof magnitude differences with a singlepeak at m 1 m2 = 0. Examples ofmagnitude difference histograms areshown in Figure 2.

Differential number counts in a71 arcmin2 area of Groth are shownin Figure 3. The area comes from sixINGRID pointings, from which theedge areas with lower exposure timehave been excluded. Similar countswere obtained for the 47 arcmin2

mapped in the Coppi field. Our Grothcounts bridge over the magnitude rangebetween shallow, wide- area surveys,eg. Martini (2001) and deeper, pencil-beam surveys such as the one byBershady, Lowenthal & Koo (1998).There is good continuity between thethree sets of counts. Our counts inCoppi and Groth are quite close toeach other. The counts stress earlierresults that no-evolution models are

inconsistent with the counts. At thesedepths, and for this cosmology, pureluminosity evolution (PLE) modelsprovide a good fit to the counts. Wereproduce a moderate excess atintermediate magnitudes over the PLEmodels, as found by Martini (2001).

Subsequent work on the COSMOSSurvey includes covering a widerarea until the target 0.5 degree2 isreached. Progress on COSMOS maybe followed at the EMIR web site,http://www.ucm.es/info/emir/. ¤

References:

Balcells, M., 1999, Ap. Sp. Sc., 263, 361.

Balcells, M. et al., 2000, SPIE, 4008, 797.

Bershady, M. A., Lowenthal, J. D., Koo,D. 1998, ApJ, 505, 50.

Bertin, E., Arnouts, S., 1996, A&A, 117, 393.

Cristóbal-Hornillos, D. , Balcells, M., Prieto,M., Guzmán, R., 2001, Astrophysics andSpace Science Supplement, 277, 577.

Guzmán, R., Gallego, J., Koo, D. C., Phillips,A. C., Lowenthal, J. D., Faber, S. M.,Illingworth, G. D., & Vogt, N. P., 1997,ApJ, 489, 559.

Gardner, J. P., 1998, PASP, 110, 291.

Martini, P., 2001, AJ, 121, 598.

Stanford, S. A., Eisenhardt, P. R. M.,Dickinson, M. E., 1998, ApJ, 492, 261.

Steidel, C. C., et al., 1996, ApJ, 462, L17.

Marc Balcells ([email protected])


1 2

Figure 1. An 11.4"x 5" field inthe Groth stirp, imaged in theKs NIR band by INGRID (top)and in the F606W filter byHST/WFPC2. The INGRIDexposure was 1.5 hr on-targetintegration. Seeing was 0.65"FWHM in the coadded image(pixel size 0.24 arcsec). Onsuch images, we reach 50%detection efficiency at K∼ 20.8.The low-inclination spiral in thelower left is clearly blue, while,next to it, an elongated object,seemingly another spiral, haspronounced redder colours.


1 3

Figure 2. Histograms used in identifying spurious sources. After SExtractor has produced a source catalogue from the total-exposure image, we perform photometry at the same source positions on two independent images, each from a coadd totallinghalf the total exposure time. We select sources for which the SN in any one of the two half-time measurements is lower than agiven SNlim, and plot the histogram of magnitude differences m1 m2. The first histogram used SNlim=2.8; the single peakindicates that the SNlim=2.8 cutoff selects many sources for which m1m2~0, two independent measurements consistent witheach other which indicate that the sources are real. The second histogram used SNlim=1.6; the double peak indicates thatSNlim=1.6 correctly isolates spurious sources.

Figure 3. Number counts obtained on the Groth strip. The figure gives number ofgalaxies per square degree per magnitude interval. Counts are corrected for efficiencyand for spurious sources. Efficiency correction is performed only for magnitude binswith a detection efficiency above 50%. Error bars are 1-σ upper- and lower-confidenceintervals (84.13% confidence level). Superimposed on the counts are three referencenumber count predictions, which we derive using ncmod (Gardner, 1998).

Satellites and Tidal Streams ConferenceWe are pleased to announce the conference Satellites and Tidal Streams, organised by the Isaac Newton Group of Telescopes (ING) andthe Instituto de Astrofísica de Canarias (IAC), to be held on the island of La Palma on May 2630, 2003.

Current cosmological models predict that galaxies form through the merging of smaller substructures. Satellites and tidal streams mightthen represent the visible remains of the building blocks of giant galaxies. They therefore provide important information on the merginghistory and galaxy formation in the Universe. In this conference the observational evidence for substructures, their internal structure andtheir dynamical evolution and disruption within the tidal field of the host galaxy will be discussed and confronted with theoreticalcosmological predictions of hierarchical merging and galaxy formation. Topics that will be discussed include: satellites of galaxies: brightand dark, the dark matter content of dSph and LSB galaxies, tidal streams: probes of the structure and formation of the Milky Way andother Nearby Large Galaxies, predictions of Cold Dark Matter models on small scales, compact HVCs and galactic substructure and masssubstructure from gravitational lensing.

To achieve these goals, invited reviews and talks given by leading scientists in all the fields above are planned, as well as a number ofcontributed talks and posters presenting the recent results from the relevant fields. A preliminary list of invited speakers is: R. Braun(NFRA, The Netherlands), A. Burkert (MPIA, Germany), E. Grebel (MPIA, Germany), R. Ibata (Observatoire de Strasbourg, France),M. Irwin (IoA, UK), K. Johnston (Wesleyan University, USA), A. Klypin (NMSU, USA), D. Lynden-Bell (IoA, UK), S. Majewski(University of Virginia, USA), M. Mateo (University of Michigan, USA), B. Moore (University of Zurich, USA), J. Primack (University ofCalifornia at Santa Cruz, USA), P. Schneider (Bonn University, Germany), S. White (MPA, Germany), R. Zinn (Yale University, USA).

You will find more information on the conference web site at: http://www.iac.es/proyect/sattail/

Registration opens on Thursday November 14th. The deadline for registration is April 1, 2003. The list of speakers, posters, etc. will befinalized after this deadline. Note that the total number of participants will be limited to 120. ¤

Francisco Prada and David Martínez-Delgado, Co-chairs SOC ([email protected])

targets show strong Ly-α and CIVemission lines which, at redshifts∼ 2 4, fall in our wavelengthresponse range.

Information on each detected photonconsists of arrival time, coordinatesof the junction, and an energy channelE in the range 0255. Laboratorymeasurements have confirmed thatall junctions have a highly linearenergy response, so that an incidentphoton of energy Ep is assigned to anenergy channel E ∼ 42.5· Ep[eV] 2.0(de Bruijne et al., 2002).

Results

We determined quasar redshifts z byfitting the calibrated observed energydistributions with a single templateHST quasar spectrum, i.e., byminimising the function χ2(z) (deBruijne et al., 2002). Examples ofobserved and modelled spectra areshown in Figure 1. The overall shapeof these spectra, in particular thefalloff at low energy channels (longwavelengths), is due to the combinedresponse of the instrument andtelescope. In practice, the Ly-α lineand the associated break at shorterwavelengths contribute most to theredshift determination.

Figure 2 compares the best-fitredshifts with the literature values.QSO 0127+059 is our single prominentoutlier. It was discovered in a thinprism survey, classified as a possiblequasar, and tentatively assigned aredshift of z ≈ 2.30 with a questionable


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SCIENCE

Quasar Redshifts from S-CAM Observations:Direct Colour Determination of ~12 Gyr-Old Photons

Jos H. J. de Bruijne1, A. P. Reynolds1, M. A. C. Perryman1,2, A. Peacock1, F. Favata1, N. Rando1,D. Martin1, P. Verhoeve1, N. Christlieb3

1: Research and Scientific Support Department of the European Space Agency. 2: Sterrewacht Leiden. 3: Hamburger Sternwarte

C CDs have revolutionisedastronomy in the last quarterof the 20th century, yet

measuring energy distributions ofcelestial objects still requires theindirect methods of filter photometryor dispersive spectroscopy. Thedevelopment of superconducting tunneljunction (STJ) detectors (Perrymanet al., 1993; Peacock et al., 1996, 1997)has opened up the possibility ofmeasuring individual optical photonenergies directly. The first time-andspectrally-resolved observations ofcataclysmic variables and pulsars usingthese techniques have been reported(e.g., Perryman et al., 1999, 2001;Bridge et al., 2002), and the first directmeasurements of the redshifts ofquasars using an imaging detectorwith intrinsic energy resolution werepublished early this year (de Bruijneet al., 2002; cf.http://astro.esa.int/SA-general/

/Research/Detectors_and_optics/).

Observations

We observed 11 Lyman-limit quasars,selected from the literature in therange z = 2.2 4.1, using S-Cam2(Rando et al., 2000) on the WilliamHerschel Telescope in October 2000.S-Cam2 is a 6×6 imaging array of25×25 µm2 (0.6×0.6 arcsec2) tantalumjunctions, providing individual photonarrival times to ∼ 5 µs, a resolvingpower of ℜ ∼ 8 at 500 nm, and a highsensitivity from the atmospheric cutoffto ∼ 720 nm (this cutoff is currentlyset by long-wavelength filters whichreduce thermal noise photons). All

line identification. Our fit provides agood representation of the data(Figure 1), yet the derived redshift,z = 2.976, differs significantly from theliterature value. We therefore obtaineda spectrum of this object with theSiding Spring Observatory 2.3-mtelescope, from which a redshiftz = 3.04 was deduced, in excellentagreement with our estimate !

As all fits have reduced χ2>>1, noneof them is formally acceptable. Thegeneral consistency between the modelsand the observations, combined withthe pronounced, deep and narrow,minima in all χ2(z) plots, nonethelessindicates that our model fits the datawell. Small systematic errors relatedto, e.g., template mismatch, are,although largely hidden due to thelimited detector resolution, the key tothis paradox (de Bruijne et al., 2002).

Discussion

Pronounced χ2(z) minima arealready present in our datatruncated a posteriori to observationtimes as small as, e.g., 1020s forQSO 0000263 (z = 4.1; V =17.5 mag),where ∼ 350 source photons s1 wererecorded (Figure 3). We thereforeconclude that efficient low-resolutionspectroscopy of faint extragalacticsources is possible with STJ devices,enabling the determination of redshift.Extraction of detailed physicalinformation from the spectra presentedhere is limited by the modest resolvingpower of S-Cam2 (ℜ ∼ 8). A significantimprovement in energy resolution is,


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however, foreseen in the future (e.g.,Rando et al., 2000), promisingenhanced physical diagnosticcapabilities. It has, for example, beenshown that an STJ detector withℜ ∼ 20 would allow the determinationof galaxy morphological type andperhaps emission and absorption lineratios (Jakobsen, 1999; Mazin &Brunner, 2000).

STJ instrument development withinESA is currently also aimed atproducing larger format arrays, tofacilitate sky subtraction and possiblyallow for multi-object spectroscopy,and at extending the wavelengthresponse further to the red. The latterobjective, which is consistent withthe fundamental device responsecharacteristics, would open up alarger accessible redshift range.

Acknowledgments

We acknowledge the ING staff fortheir excellent support during theS-Cam observing campaigns. ¤

Figure 1. Results for QSO 0127+059, 0148 097, and0642+449. Left: observed (black) and modelled (grey)energy channel distributions (arbitrary units). Our modelis based on a single template HST quasar spectrum.Insets indicate the Poisson noise. Numbers above thetop left panel show the mapping between energy channeland wavelength. Right: the corresponding dependenceof χ2 on z. Vertical dashed lines indicate the literatureredshifts; the dotted line for QSO 0127+059 indicatesz = 3.04 (see text).

Figure 2. Observed versus literatureredshifts. Numbers refer to theobjects (de Bruijne et al., 2002).Symbol sizes correspond to χ2 ;smaller symbols indicate a poorerfit. QSO 0127+059 has an incorrectliterature redshift of 2.30; follow-upspectroscopy has yielded z = 3.04,moving the point to the positionshown in grey. The dashed line showsthe 1:1 correlation.

References:

Bridge, C. M., et al., 2002, MNRAS,submitted.

de Bruijne, J. H. J., et al., 2002, A&A,381, L57.

Jakobsen, P., 1999, in ASP Conf. Ser.,164, 397.

Mazin, B. A., Brunner, R. J., 2000, AJ,120, 2721.

Peacock, A., et al., 1996, Nature, 381, 135.

Peacock, A., et al., 1997, A&AS, 123, 581.

Perryman, M. A. C., et al., 1993, Nuc.Inst. Meth. A, 325, 319.

Perryman, M. A. C., et al., 1999, A&A,346, L30.

Perryman, M. A. C., et al., 2001, MNRAS,324, 899.

Rando, N., et al., 2000, in SPIE Proc.,4008, 646.

Jos de Bruijne ([email protected])


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Figure 3. Top: χ2(z) using the first x=1,...,21 seconds of data of QSO 0000 263 (z =4.1). Thedashed and solid lines indicate the literature and best-fit redshifts, respectively. Bottom: as toppanels, but showing the observed QSO spectra (black) and best-fit models (grey). Panels havediffering vertical scales.

The CIRSI-INT IR Survey

R. G. Sharp, R. G. McMahon, S. Hodgkin and C. D. Mackay (Institute of Astronomy,University of Cambridge)

CIRSI-INT IR Survey

With a field of 4 ×7.80 ' ×7.80 ' at theprime focus of the 2.5m Isaac NewtonTelescope, the Cambridge InfraRedSurvey Instrument, CIRSI (Mackayet al., 2000), is currently the largestfield of view IR imager in operation.The camera, a mosaic of 4 RockwellHgCdTe HAWAII IR arrays, iscapable of observing in the J and Hbands at the INT. The physicalconstruction of the detector arraysprevents them being butted together

T he Isaac Newton Telescopehas been used in conjunctionwith the Cambridge InfraRed

Survey Instrument (CIRSI), toundertake a wide area deep IRsurvey in the J and H bands. Thisarticle gives a brief introduction tothe survey and presents some initialresults. In the spirit of the INT WideField Camera Survey program (Waltonet al., 2001;http://www.ing.iac.es/Astronomy/

/science/wfs/;http://www.ast.cam.ac.uk/~wfcsur/)we are making reduced data products

publicly available. A preliminary datarelease is planned for April 2002 witha complete release planned in theSummer 2002. The survey observationshave been used in conjunction withoptical CCD data from the INT WideAngle Survey to undertake a surveyfor low and intermediate redshiftquasars (z < 3) free from the potentialbiasing effect of dust absorption. Theresults of these observations arereported to illustrate the utility ofthe survey data for combined optical-IR survey projects.

Note from the editor: article received in March 2002

release from the Sloan Digital SkySurvey (SDSS).

Example Science:Reddening IndependentQuasar Selection

It has long been known that absorptionby dust, if present either along theline of sight to quasars or within thequasar host galaxies themselves, couldbias samples of quasars selectedprimarily on the bases of ultravioletexcess (UVX). Figure 3 demonstratesthe predicted effects of dust reddeningon UVX selection of quasars. Two ofthe quasars identified in the CIRSI-INT sample for which U bandobservations are currently availabledo not show a UV excess. There are anumber of reasons to endeavor toconstruct a quasar sample free froma bias against dusty quasars. Twoexamples are the following:

There is an apparent lack of highcolumn density ( log N(HI) > 21cm2)damped Lyman-α (DLA) quasarabsorption systems observed withhigh metallicity (Boisse et al., 1998).

If the dust within DLA absorptionsystems themselves is responsiblefor reddening quasars then moreevolved DLA hosts with highermetallicities could well be expectedto exhibit higher dust content andgreater dust obscuration of thebackground quasar, preventing themost evolved DLA systems frombeing discovered.

Dust may bias quasar lensingstatistics (Kochanek, 1996). If theidentification of quasars is biasedagainst objects lensed by dustylenses then any model associatedwith the population of lensedquasars is also biased. Recentlymultiply imaged lensed quasarshave been used to study the structureof distant galaxies by detailedstudies of quasar absorption linesystems. If lensed quasar samplesare biased against dusty lens thenthese studies will only investigatesystems with little dust.

Figure 4 illustrates the principle of theg z H colour selection techniquedeveloped for defining quasarcandidates. The principle is similar tothe VJK selection method proposed


1 7

in close proximity as is normal foroptical CCD mosaic cameras. Thereis a 90% spacing between the elementsof the mosaic. Sequential observationsare offset to fill the gaps in the mosaic.A 4 pointing tile of observations coversan area of 29.6'×29.6'. Figure 2demonstrates the camera layout.

The nominal survey depths attainedare J< 20.0, H<19.0 roughly threemagnitudes deeper than the levelattained by the 2MASS project. Detailsof the fields observed are given inTable 1. The survey observing strategyconsists of ∼ 350 sec exposures.Depending on sky brightness conditionsduring observations the exposure isbuilt up from a sequence of 4 (or 5)dither positions with 4 (or 3) exposuresof 22 s (or 30 s) duration at eachposition. Approximately 5 Gb of dataare obtained a night. Data processingis performed using pipeline processingsoftware developed in Cambridge(Sabbey et al., 2001).

INT WAS Data

The fields targeted by the CIRSI-INTsurvey program are chosen to becoincident with observations from theINT Wide Angle Survey project(McMahon et al., 2001). The INT WASfields surrounding the ISO ELAISN1 and N2 fields at 1610+54 and1637+41 have been extensivelyobserved in the J and H bands andobservations have also beenundertaken in the J band of the zerodeclination strips at RAs of 14:55 and22:08, coincident with the recent data

Figure 1 (left). CIRSI at the prime focus of the 2.5m INT. Figure 2 (right). The image to the left is a 29.6'×29.6' mosaic of fourpoinitngs of the CIRSI camera. To the right the weight map associated with the mosaic is shown.

Field RA Dec (J2000) Depth Extent

INT WAS ISO ELAIS N1 16:10 +54:30 J< 20.0, H<19.0 7deg2

INT WAS ISO ELAIS N2 16:37 +41:16 J< 20.0, H<19.0 7deg2

INT WAS NGC 14:5214:58 +00:00 J<20.0 3deg2

INT WAS SGC 22:0022:16 +00:00 J<20.0 2deg2

Table 1. Survey regions and observational data available. The North and SouthGalactic Cap regions (NGC/SGC) are coincident with the recently released SDSSzero declination strip observations.

by Warren, Hewett & Foltz (2000),however, observations are required inonly one IR band. A preliminary quasaridentification has been undertaken bySharp et al. (2002). 68 candidate quasarare identified in data taken from asubset of 0.7 deg2 of the availablesurvey area. Spectroscopic observationsof 32 targets have been obtainedconfirming 22 quasars, a success rateof 65%. Observations are currentlyavailable across the ugrizJ and Hbands for a sub set of the quasarsidentified. The ugr colour diagram,analogous to the traditional UVXquasar colour selection scheme, isshown in Figure 3. Two of the newlydiscovered quasars show no UV excessat all. ¤

References:

Boisse, P., Le Brun, V., Bergeron, J.,Deharveng, J., 1998, A&A, 333, 841.

Boyle, B. J., Shanks, T., Croom, S. M,Smith, R. J., Miller, L., Loaring, N.,Heymans, C., 2000, MNRAS, 317, 1014.

Kochanek, C. S., 1996, ApJ, 466, 638.

Mackay, C. D., McMahon R. G., Beckett,M. G., Gray, M., Ellis, R. S., Firth, A.E., Hoenig, M., Lewis, J. R., Medlen, S.R., Parry, I. R., Pritchard, J. M., Sabbey,C. S., 2000, SPIE, 4008, 1317.

McMahon, R. G., Walton, N. A., Irwin, M.J., Lewis, J. R., Bunclark, P. S., Jones,D. H., 2001, NewAR, 45, 97.

Sabbey, C. N., McMahon, R. G., Lewis,J. R., Irwin, M. J., 2001, ASP Conf. Ser. ,238, 317.

Sharp, R. G., McMahon, R. G., Irwin, M. J.,Hodgkin, S. T., 2001, MNRAS, 326, L45.

Sharp, R. G., Sabbey, C. N., Vivas, A. K.,Oemler, A. Jr., McMahon, R. G., Hodgkin,S. T. and Coppi, P. S., 2002, MNRAS,submitted.

Walton, N. A., Lennon, D. J., Irwin, M. J.,McMahon, R. G., 2001, ING Newsl., 4, 3.

Warren, Hewett & Foltz, 2000, MNRAS,312, 827.

Robert Sharp ([email protected])


1 8

Pixel scale (arcsec/pixel) 0.46FOV per chip 7.8' × 7.8'FOV for 2×2 mosaic 29.6' × 29.6' Frames/deg2 16J, 5min 5σ in 1.2'' seeing 20.0H, 5min 5σ in 1.2'' seeing 19.0

Table 2. CIRSI Characteristics on 2.5-mIsaac Newton Telescope.

Figure 3. A comparison is shown of a sample of previously known quasars identifiedin the SDSS. The new quasars identified by gzH selection for which ugr data isavailable from the INT WAS are marked with filled circles. The horizontal line atu g= 0.3 represents a UVX selection boundary analogous to that used in the 2dFquasar survey (2QZ Boyle et al., 2000). The stellar locus, computed from a spectralatlas, is shown along with stellar objects from a field of the INT WAS. The locus ofquasar colour as a function of redshift is indicated by the solid line. The onset ofabsorption in the g band, due to the Lyman-α forest, is evident for quasars withz>3. Reddening vectors for dust models based on the Galaxy and the SmallMagellanic Cloud are shown over a range of redshifts. The 2175Å feature in thegalactic law passes through the g band over the range 1< z<2.

Figure 4. The candidate selection diagram for a 0.17deg2 region of the survey isshown with the full quasar sample overlaid. The selection boundary, chosen basedon model quasar colours, is indicated by the broken line offset from the linear fit tothe stellar locus.

Probably the most important changeis presented by the fact that theInstituto de Astrof ísica de Canariaswill become a full partner in ING asof 2002. An agreement was reached,with strong support from the INGBoard and the UK and NL fundingagencies, on the terms under whichthe IAC would join in the operatingcosts of ING. This agreementsignificantly alleviates the impact ofthe budget reductions announced byPPARC and allows ING to remain astrong and vibrant organisation thatcan deliver quality service to its usercommunity. The tight collaborationwith the IAC is of strategic importanceas this institute fulfills a pivotal rolein the development of the observatorysite, in particular with the constructionof the 10-m GRANTECAN and itsplans to create a Europeancollaboration for observing facilitiesin the Northern hemisphere. Moreover,the IAC is developing a newobservatory centre at sea level on LaPalma, in which the ING willparticipate. But nevertheless, thefuture budget available to ING for theoperation of the telescopes will reduceby more than 30%, in spite of theadditional contribution of the IAC.The IACs contribution will commencein 2002, and the Netherlands willleave its annual contribution largelyunchanged. This large decrease inthe operational budget and the changeof balance between the internationalpartners implies a number of

important changes, that can besummarised as follows:

1. Balance of Observing Time

The balance of observing time willgradually change over the followingyears. The agreed percentagebreakdown of observing time will beas follows (see Table 1).

2. Service Observations

The existing scheme of serviceobservations that are carried out byobservatory personnel will bediscontinued on the JKT from theend of semester 02A and on the INTfrom the end of semester 03A. Onthe WHT service observation willremain available.

3. Use of the JKT and INT

The JKT will be taken out of normalservice as of September 2003. Possiblythis telescope will continue as aspecial-purpose telescope with externalfunding. But if no additional resourcescan be found the JKT will close. It isthe intention to review the longerterm future of the INT before the endof 2004. By that time various othertelescopes will be carrying out imagingsurveys and the Liverpool telescopewill be well established, making ittimely to review the scientific use ofthe INT. Until that time, operation ofthe INT will have to be carried out ata lower cost. Cost saving measuresenvisaged are to operate the INT with


1 9

TELESCOPES AND INSTRUMENTATION

The ING Telescopes in a Changing Landscape

René G. M. Rutten (Director, ING)

L andscapes in geological termstend to change slowly, unlessthere is a land slide. With the

UK joining ESO the focus of UKground-based astronomy will changein a dramatic way as well,strengthening its European focus. OnDecember 5th 2001 PPARC Counciltook a number of important decisionsrelated to the UK joining ESO. Thesedecisions will have a profound impacton various existing facilities, includingthose of the ING. PPARCs wayforward reflects the reality of therapidly changing environment ofground-based astronomy, with thedeployment of several 8-m classtelescopes and the adhesion of theUnited Kingdom to the EuropeanSouthern Observatory. Furtherreference to the Councils decisioncan be found in this PPARC pressrelease http://www.pparc.ac.uk/NW//ESOstars.asp.

Impact of BudgetReductions

It has been apparent for some timethat the annual operating budget forING would come under pressure, inparticular as the UK has to free upfunds to contribute towards the annualcost of joining ESO. Over the pastyear, plans have been developed onhow ING could be operated within areduced budget. Central in these plansis the improved collaboration withthe Instituto de Astrof ísica deCanarias. The ING Board has playeda very active role in securing anagreement of principles of how in thefuture PPARC, NWO and the IACcould collaborate in the operation ofthe ING. The decision from PPARCCouncil is in line with these plans.

The key elements of the changes thatthese plans entail are presented here.

2001 2002 2003 2004 20059

UK 60.0 54.0 50.0 48.9 47.6NL 15.0 15.0 15.9 17.0 18.3CAT Spanish additional time 0.0 6.0 9.1 9.1 9.1CAT Spanish time 20.0 20.0 20.0 20.0 20.0CCI international time 5.0 5.0 5.0 5.0 5.0

Table 1. Percentage breakdown of observing time.

only the Wide Field Camera fromsome time in 2003 onwards, and atthe same time fully withdraw telescopeoperator support from that telescope.

4. Use of the WHT

The focus of support and developmentwill shift fully towards the WHT inorder to keep that telescope asattractive as possible to the community.Although scheduling flexibility andinstrument changes may have to bemore strictly limited, the servicedelivered will be enhanced throughthe introduction of queue observingmode for up to 30% of the time on theWHT. Primarily queue observing willfocus on adaptive optics observations.

5. A Common-User IR Imager andSpectrograph

As part of the agreement with the IAC,the LIRIS IR imager and spectrographthat is currently being developed at theIAC will be made available to thegeneral user community for at least3 years after commissioning andacceptance. Commissioning of LIRISis anticipated to take place at thebeginning of 2003. Given the popularityof INGs IR imager, we expect thatthis new instrument will attract muchinterest from the user community.

The changes mentioned above focus onthe impact that the budget reductionswill have on the use of the telescopes.Not mentioned here are the complexinternal changes that will beimplemented and cost saving measuresin the way ING operates. It is ourintention to minimise the disruptionto normal day-to-day operation ofthe telescopes as much as possible,and ING remain dedicated to deliverthe best possible service to ouruser community.

Collaboration BetweenObservatories

In the European astronomical arenainternational collaborations areemerging between national facilities.These collaborations have beenpromoted and supported by theOPTICON European network, which

combines astronomers from manyEuropean countries and is fundedthrough the EU (seehttp://www.astro-opticon.org).An important driver for setting upcollaborations between observatoriesis the wish to make the bestinstruments available to the widercommunity of astronomers for theadvancements of our science, and tomake the existing facilities work moreefficiently in the process. Duplication ofinstrumentation with the consequentialcosts could be avoided, thus providinga better service to the community at alower overall cost.

A few specific collaborations betweenthe ING telescopes and other telescopesare being considered. One particularcollaboration is to share observingtime between the WHT and the ItalianGalileo telescope, TNG, on La Palma.This collaboration centres on the useof the high-resolution spectrographon that telescope, as the UES echellespectrograph on the WHT will not beoffered for some time.

Other collaborations currently underconsideration are with the 3.5-mCalar-Alto telescope, with the Canada-France-Hawaii Telescope, and withthe Nordic Optical Telescope.Discussions with these facilities arestill at an early stage. In any case,for such collaborations to come intoeffect there must be a clear advantagefor our community of telescope users.The above mentioned arrangementwith the TNG is a good example, where

without this arrangement theopportunity for high-resolutionspectroscopy would have been lost.

The Utrecht EchelleSpectrograph

The longer-term availability of ahigh-resolution spectroscopic facilityis under study. The Nasmyth focalstation currently occupied by theUtrecht Echelle Spectrograph willbecome a dedicated focus for adaptiveoptics instrumentations. For thatreason the UES will be taken awayfrom the telescope, but not necessarilybe simply decommissioned. Apartfrom decommissioning there arecurrently two options. One optionwould be to enhance the instrumentwith an image slicer and fibre opticsfeed improving its spectral stability.The instrument would then be placedin a stable and controlled environment.The second option under study is thepossibility to deploy UES on the10-m GRANTECAN telescope, alsofed by fibres.

Both options carry attractivepossibilities, but first technical aspectswill have to be explored. Apart fromthe technical and astronomicalprospects, under the much tighterfuture operational budgetary regimeaspects of operational efficiency andstream lining will become ever moreimportant aspects for ING. ¤

René Rutten ([email protected])


2 0

As part of the reestructuring plan, both the Jacobus Kapteyn Telescope (September2003) and the Utrecht Echelle Spectrograph (July 2002) will be taken out ofnormal service.

seeing monitor, RoboDIMM, hasrecently been brought into use.RoboDIMM (Augusteijn, T., 2001,ING Newsl., 4, 27), delivers ameasurement of the seeing every fewminutes, from a small telescopeoutside the WHT building. ¤

Chris Benn ([email protected])

from UCL. OSCA offers 6 focal-planestops with diameter ranging 0.22.0arcsec. OSCA is offered to observerson a shared-risks basis in 2003A. Forfurther information, see the OSCAweb page: http://www.ing.iac.es//Astronomy/instruments/osca/.

At the end of 2002, NAOMI will moveto a new purpose-built enclosure,GRACE, on the opposite Nasmythplatform (the platform formerlyoccupied by UES). NAOMI will stayin GRACE permanently, and will bejoined by a second science instrument,OASIS, mid-2003. OASIS is the opticalintegral-field spectrograph formerlyat CFHT. NAOMI will deliversignificant adaptive-optics correctionat optical wavelengths, permittingOASIS spectroscopy of galaxies (andother targets) at high spatial resolution.

The GHRIL enclosure will revert toits original function of hosting visitinginstruments and experiments,including further tests by DurhamUniversity of wavefront correctionusing a Rayleigh laser beacon.

In support of future adaptive-opticsobservations, and in particular inpreparation for extensive queueobserving, a robotically-operated


2 1

NAOMI Common-User Adaptive Optics at the WHT

C. R. Benn, S. Els, T. Gregory, R. Østensen, F. Prada (ING), R. Myers (University of Durham)

Left: Figure 1. N6543 planetary nebula in Paschen beta, 600-sec integration, usingcentral star (V=11) as a wavefront reference. Adaptive-optics correction from 0.7 to0.3arcsec. The finest structures visible in the nebula are ∼ 0.3arcsec across. Imageis 30arcsec top to bottom. Right: Figure 2. NAOMI in GHRIL. INGRID is in theforeground.

Figure 3. RoboDIMM tower, dome andtelescope.

N AOMI, the WHTs adaptive-optics system, is now beingused routinely with INGRID,

the IR camera, to obtain near-diffraction-limited images atwavelengths 12.2 micron (J, H, K,and narrow-band filters). Timeallocations are queue-scheduled to takeadvantage of the best seeing, butvisiting observers are also welcome.The images reproduced here and onthe front page are from the May 2002commissioning run. With bright guidestars (V<11), NAOMI improves imageFWHM from 0.7 to 0.2 arcsec in J, Hand K bands. For V ∼ 12, the correctionis typically from 0.7 to 0.3 arcsec, anduseful correction has been obtainedfor guide stars down to V ∼ 13.5. Anuncorrected seeing of 0.7arcsec in Hband corresponds to 0.9 arcsec in V,well above the median for the site(0.7arcsec). A summary of measuredperformance (FWHM, FWHE, Strehl)can be found on the NAOMI web page:http://www.ing.iac.es//Astronomy/instruments/naomi/.

Near Earth Asteroid 2002 NY40 wasobserved with NAOMI on the night17 August 2002, just before its closestapproach to earth. This is the firsttime an NEA has been imaged withan adaptive-optics system. The asteroidwas only ~750000km away duringobservation, and moving across thesky at about 5arcsec per second.Despite the technical difficulties thisintroduced, H-band images wereobtained with a resolution of 0.11arcsec,close to the diffraction limit of theWHT. This sets an upper limit of 400mon the projected size of the asteroidat the time of observation.

NAOMIs emissivity in K-band is stillhigh (~100%), so programmes whichcan be observed in either H or K areprobably best done in H until theemissivity has been reduced.

NAOMIs coronograph, OSCA, wassuccessfully commissioned in May2002, by Peter Doel and his team


2 2

LIRIS: A Long-Slit Intermediate Resolution InfraredSpectrograph for the WHT

José Acosta-Pulido1, E. Ballesteros1, Mary Barreto1 (Project Manager), Santiago Correa1, JoséM. Delgado1, Carlos Domínguez-Tagle1, Elvio Hernández1, Roberto López1, Arturo Manchado1

(Principal Investigator), Antonio Manescau1, Heidy Moreno1, Francisco Prada2, Pablo Redondo1,Vicente Sánchez1, Fabio Tenegi1.

1: Instituto de Astrofísica de Canarias; 2: Isaac Newton Group of Telescopes

L IRIS is an Instituto deAstrof ísica de Canarias (IAC)project that consists in a near-

infrared (0.92.4microns) intermediateresolution spectrograph, conceivedas a common user instrument forthe WHT.

LIRIS will have imaging, long-slit andmulti-object spectroscopy observingmodes (ℜ ~1000 3000). Coronography,and polarimetry capabilities willeventually be added. Image capabilitywill allow easy target acquisition forspectroscopy.

1. Scientific Drivers

Given its common-user status, it shouldbe possible to use LIRIS for a widerange of astrophysical disciplines,including the areas of stellar,planetary, extragalactic andcosmological physics. We list belowsome of the most relevant potentialscientific applications:

Spectroscopy of proto-planetarynebulae.

Detection of very low masssecondaries, planets and browndwarfs.

Spectroscopy of nearby and distantgalaxies with massive star formation:nearby HII regions and distantstarbursts.

Stellar kinematics and populationsin spiral galaxies.

Physical conditions of the gas, andthe stellar kinematics andpopulations of starburst galaxiesand AGNs.

Ultraluminous infrared galaxies.

The fundamental plane of high-redshift elliptical and S0 galaxies.

Redshift measurements of infraredsources.

2. General Description

The optical system is based on aclassical collimator/ camera design(Figures 1, 2 and 3). The expectedthroughput (averaged across thewavelength range) for the optics is 80%and 64% in imaging and spectroscopicmodes, respectively. The totalthroughput including filters, grismsand detector is 35% and 30% inimaging and spectroscopic modes,

respectively. Grisms are used as thedispersion elements (the grismtransmission is assumed to be 80%).Low resolution grisms aremanufactured in Corning 9754(Figure 4) while medium resolutionwill be manufactured in ZnSe. A setof filters (broad band, Z, J, H, Ks andnarrow band Br-α, K-continuum,H-continuum, [FeII], H2 (v=1 0),H2 (v=21), CH4 and HeI) have beenacquired through a consortiumheaded by Alan Tokunaga.

The mechanical design is based on amodular concept, integrated by thefollowing modules: the aperture

Focal station CassegrainArray format Rockwell Hawaii 1024×1024 HgCdTeScales at detector 0.25 arcsec/pixelObserving modes Imaging, long-slit spectroscopy, multi-object spectroscopy,

coronography with apodization masking and polarimetry

IMAGING MODE

Field of view 4.2 ×4.2 arcminSensitivity K=22.13, H=23.68, J=24.75, Z=25.24 for t=1h, S/N=3, 0.5 seeing

SPECTROSCOPY MODE

Available slits Long slit: (0.5, 0.75, 1, 2.5, and 5) arcsec ×4.2 arcminMulti-object: 10 multislit masks available (up to 24 slits per mask)

ℜ =1000Bands Z and J (0.8871.531 mm). Limiting magnitudesJ=21.3, Z=22.0

Spectral Bands H and K (1.3882.419 mm). Limiting magnitudescoverage and K=18.6, H=19.9 sensitivity* ℜ =3000

Bands Z (0.997 to 1.185 mm). Limiting magnitude Z=21.2Bands J (1.178 to 1.403 mm). Limiting magnitude J=20.3Bands H (1.451 to 1.733 mm). Limiting magnitude H=19.5 Bands K (2.005 to 2.371 mm). Limiting magnitude K=18.0

*In all cases for the continuum and t=1hr, S/N=3, FWHM=0.5"

Table 1. Instrument features.

Note from the editor: article received in March 2002

wheel (slit wheel), the collimatorassembly, the central wheel assembly(formed by two filter wheels, the pupilwheel and the grism wheel), thecamera wheel and finally the detectorassembly with its focussing mechanism.The detector will be mounted in a coldtranslation mechanism to compensatefor non-achromaticity along theobserving spectral range.

The detail optical design and theconceptual mechanical design weresubcontracted to the ROE (RoyalObservatory of Edinburgh).

The slit wheel (Figure 5) contains 16positions: one blank position, five longslits and ten multislit positions. Thetwo filter wheels contain 12 positionseach, and will hold the filters and theWollaston prisms. The pupil wheel(Figure 6) contains 12 positions andwill hold the pupil masks, plus anoptional apodization mask withrotation mechanism for coronographycapabilities. The grisms wheel has 10positions for grisms. The camera wheel(Figure 7) has four positions and willcarry the camera and the optics to re-

image the pupil onto the detector plane,as well as an aperture and a blackaperture. All mechanisms usePhytron cryogenic stepping motorsand the control system is based on aVME system.

The instrument is pre-cooled with LN2,and the cooling system is a two-stageclosed-cycle refrigerator (Figure 8)(CTI model 1050C), which works onthe Gifford-McMahon cycle.

The detector is a Hawaii 1024×1024HgCdTe array using a SDSUcontroller, which communicates withthe control computer (SUNworkstation) using the SBUS card.

An agreement has been establishedbetween the IAC and the ING todevelop jointly the detector control

system and the Mechanism ControlSoftware for the two infraredinstruments (LIRIS/ IAC andINGRID/ING).

The LIRIS Software system is beingdesigned to be fully integrated in theobserver environment available atthe WHT. A common observer willhave access to the following softwarepackages: Instrument SimulatorSoftware, Templates GeneratorSoftware, Instrument Support PlatformUser Interface, LIRIS Mechanism andThermal Control Software, Real TimeDisplay, Quick Look Data Analysisand Pipeline Data Reduction.

3. Current Status

At present LIRIS is in the calibrationphase at IAC. Assembly, integration


2 3

Figure 1. LIRIS schematic representation.

From left to right: Figure 2. Collimator. Figure 3. Camera. Figure 4. Corning 9754 Gris.

and verification phases were carriedout in summer 2001.

The collimator, camera, slits wheelmechanism and the main centralwheel (filter 1 and the pupil wheel)mechanism have been successfullytested at test cryostats (Figure 9) incryogenic conditions. They have alsobeen pre-integrated on LIRIS to checkthe interfaces (Figures 10, 11 and 12).

Test multi-slits masks have beenmanufactured by Electric DischargeMachining (EDM) and successfullytested achieving a roughness of1.15±0.15 microns.

The engineering and the scientificdetectors have been tested in cryogenicconditions on a purpose-built detectortest bench (Figures 13 and 14). Themain characteristics of the sciencedegree array at 80 K are as follows:readout noise ∼ 20e, dark current0.065 e s1, bad pixels <1.5% and thedetector behaves linearly within 2%up to 50% of the full-well (175,000 e).The signal offset was found to vary670 e/K with the detector temperature.The current temperature controllerpermits a stability of better than0.005 K, which implies a signal offsetvariation of less than 4 e.

In November 2001 the LIRIS Cryostatintegration was started (vacuum tank,optical bench, closed-cycle cooler,radiation shields, etc.) (Figures 15,16, 17 and 18) and in December thefirst cool-down was successfullycompleted (Figures 19 and 20).

The following LIRIS cool-down tookplace in March and it included theslit wheel mechanism, collimator,central wheels mechanisms (two filterwheels, pupil and grisms wheels) andthe camera mechanism. First lightand commissioning at the telescope isexpected at the beginning of 2003.

For on-line information about theLIRIS project, please visit our website at:http://www.iac.es/proyect/LIRIS/.¤

Arturo Manchado ([email protected])


2 4

Left: Figure 8. Closed-cyclerefrigerator with the two-stagethermal links integrated. Right:Figure 9. Mechanism cryostaton the Mitutoyo during thefunctional verification of themain central wheels module.

From left to right: Figure 10. Main central wheel module (filter wheel side) pre-integratedon LIRIS. Figure 11. Bottom view of the slit wheel mechanism. Figure 12. Pre-integrationof the slit wheel on the LIRIS optical bench.

Left: Figure 13. Internal viewof the detector test cryostat.Right: Figure 14. Image of anUSAFSR pattern taken withthe scientific grade detector,through the H-band filter.

From top to bottom: Figures 15 and 16.Positioning the optical bench on thetrusses in the vacuum tank central ring(cables provisionally fixed for this cycle).Figures 17 and 18. Optical bench withthe collimator and reticules placed inspecific positions to check theirbehaviour during the first cycle (thesereticules were visible at all time througha very useful cryostat auxiliary window,see Figure 18). A simulation of thedetector module was placed outside thebeam line to test the detector thermalcontrol system.

Left: Figure 19. LIRIS cryostatready for the first cycle. Right:Figure 20. Pre-cooling withliquid LN2.

From left to right: Figure 5. Slit wheel. Figure 6. Pupil wheel. Figure 7. Camerawheel integrated in the test cryostat (dummy on camera position).

current. This figure is much less thanthe faintest sky recordable with theWHT and hence dark current is aninsignificant noise source withULTRACAM. The readout noise of thechips is also remarkably low justover 3 electrons when reading out at10microseconds/pixel and just under6 electrons when reading out at2microsec /pixel.

There is a great deal of flexibility inthe configuration of the ULTRACAMchips. It is possible to read the chipsout in full-frame mode without clearing(for minimum dead-time), full-framemode with clearing (for minimumexposure times), two-windowed mode,four-windowed mode, six-windowedmode and drift mode (for maximumframe rate). In each of these modes, itis possible to alter the size of thewindows, the positions of the windows,the binning factors, the pixeldigitisation speed, the gain and theclock speeds. Each image taken byULTRACAM is also time-stampedusing a dedicated GPS system to anaccuracy of better than 0.1 millisec.

Because ULTRACAM employs frame-transfer chips, the dead-time betweenexposures depends only on the verticalclocking time and is hence negligible;for the full-frame and windowed modesthe dead-time is typically 25 millisecand in drift mode it falls to a fractionof a millisecond. The maximum framerate of ULTRACAM depends on thesizes of the windows being read out;using drift mode and two smallwindows it is possible to achieve framerates of up to 300Hz. To handle suchhuge data rates (up to 3.6Mbytes/sec,i.e. up to 200 Gbytes/night),ULTRACAM uses a RAID array tostore the data, a DDS4 drive to archive

the data and, most importantly, apipeline data reduction system toenable real-time assessment and fullreduction of the light curves.

A key driver during the design of theinstrument hardware and software hasbeen simplicity, which ensures that theinstrument is as reliable, portable andupgradeable as possible. Therefore, theinstrument has no moving parts andthe CCDs are read out using an SDSUcontroller (such as the ones used onthe common-user instruments at theING) connected to a linux PC via a PCI


2 5

ULTRACAM Successfully Commissioned onthe WHT

Vik Dhillon (Univ. of Sheffield), Tom Marsh (Univ. of Southampton)and the ULTRACAM team*

*UKATC: Andy Vick, David Atkinson, Tully Peacocke, Steven Beard, Stewart McLay, David Lunney, Chris Tierney, Derek Ives;Southampton: Carolyn Brinkworth; Sheffield: Mark Stevenson, Paul Kerry, William Feline, John Kelly, Richard Nicholson, RichardFrench, Richard Pashley, Paul Kemp-Russell

ULTRACAM was successfullycommissioned on the WHT on16 May 2002, over 3 months

ahead of schedule and within budget.The instrument was funded byPPARC and designed and built by aconsortium involving the Universitiesof Sheffield, Southampton and theUKATC, Edinburgh.

ULTRACAM is a high-speed, three-colour CCD camera designed to provideimaging photometry at high temporalresolutions. The instrument is highlyportable and will be used at a numberof large telescopes around the world.On the WHT, ULTRACAM mounts atthe Cassegrain focus and provides a5 arcminute field on its three1024×1024 CCDs (i.e. 0.3 arcsec/pixel).Incident light is first collimated andthen split into three different beamsusing a pair of dichroic beamsplitters.One beam is dedicated to the SDSSu' filter, another to the SDSS g' filterand the third to the SDSS r'/ i' / z'filters, although it is possible to usedifferent filters if required. By carefulselection of glasses and coatings onthe optics and chips, we have achievedan instrumental throughput ofapproximately 50% in the green andred arms of ULTRACAM and 30% inthe blue arm. Combined with the factthat ULTRACAM mounts atCassegrain, and hence telescope lossesare minimal, we obtain a count rateof approximately 2,000 per second fora V=18 magnitude star in the V-band.

The CCDs in ULTRACAM are E2V47-20 frame-transfer devices ofexceptional cosmetic quality (grade 0)and quantum efficiency (97% at peak).The chips are Peltier and water-cooledto 233K, giving approximately0.05electrons/pixel/ second dark

Figure 1. Top: ULTRACAM mounted onthe Cassegrain focus of the WHT. Bottom:The ULTRACAM commissioning team,from left-to-right: Mark Stevenson(Sheffield), Paul Kerry (Sheffield), TomMarsh (Southampton), Marco Azzaro(ING), Vik Dhillon (Sheffield), Andy Vick(UKATC), David Atkinson (UKATC),Carolyn Brinkworth (Southampton).

interface. Furthermore, the astronomercontrols the CCD cameras using httprequests sent via a standard webbrowser, enabling ULTRACAM to beoperated remotely over the internet.

ULTRACAM has now been used for atotal of 5 nights in May 2002 (1 nightcommissioning and 4 nights PATTscience) and 13 nights in September2002 (4 nights PATT science, 6 nightsNL science and 3 nights CAT science).The instrument is working tospecification and appears to be veryreliable we lost only 30 minutes in13 nights in September 2002 totechnical downtime, which was dueto a faulty off-the-shelf ethernet card.The instrument has so far been usedto observe a wide range of astrophysicaltargets at high temporal resolution,including pulsars, eclipsing binarystars, cataclysmic variables, black-hole

X-ray binaries, neutron-star X-raybinaries and asteroseismology. Some ofthe initial results from these runs arepresented in the accompanying figures. For more detailed information onULTRACAM, including on-line signal-to-noise and frame-rate calculators,please consult the instrument webpages at http://www.shef.ac.uk//~phys/people/vdhillon/ultracam.If you are interested in usingULTRACAM on a collaborative basis,please contact Vik Dhillon([email protected]) or TomMarsh ([email protected]). ¤


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Figure 2. Top: Schematic showing thelight path through ULTRACAM. Bottom:

ULTRACAM in the test focal station atthe WHT, just prior to mounting on the

telescope (courtesy Sue Worswick).

Figure 5. Left: Light curve of thepulsating sdB star KPD2109+4401obtained by Simon Jeffery (Armagh)for use in his ULTRACAMasteroseismology project. Right: Imageof the Crab Nebula, obtained bycombining the simultaneous u', g' andr' ULTRACAM images. Fast data onthe Crab Pulsar at the centre of thisimage were obtained in order to calibratethe accuracy of the ULTRACAM GPStime-stamping.

Figure 3. Light curve of the eclipsing polarHU Aqr, which consists of a white dwarfaccreting material onto its magnetic polesfrom a red dwarf companion star. The lightcurve shows intense flickering from theaccreting poles and the eclipse of the poles(the 2-3 second transition into eclipse).

Figure 4. Light curve of the eclipsing white-dwarf/red-dwarf binary NN Ser.Each point on the graph represents a 2 sec exposure. The upper panel showsthe u', g' and r' flux versus time. The rise in the centre of the curve is due to areflection effect, where the irradiated inner hemisphere of the cooler star comesinto view. The lower panel is an expanded plot of the eclipse. The eclipse isdue to the obscuration of the hot white dwarf by the cool red dwarf and will beused to measure the masses and radii of the two stars (using a full light curvefit) and the rate at which the orbital period of the binary is decreasing.

What catches the eye is the largespherical mirror, again Zerodur, witha diameter of about 670mm and aweight including structure of about200kg. This heavy mirror is the opticalelement that is the most sensitive fortolerances of the whole camera and isalso very sensitive for temperaturechanges in position in respect to theflat mirror and detector. So theheaviest part will be adjustable in allits directions and will move in respectto the table to compensate fortemperature expansion (see the thin,long, low-expansion rod) while therest of the camera will be mostlynon-adjustable optics.

Hereafter the light goes through thesquare hole in the middle of the flatand via a field flattener lens it will beprojected into a standard ING cryostat.

The camera is optimised to use as adetector two MIT Lincoln Labs low-fringing, high-QE CCDs buttedtogether as a two chip mosaic of 4Kby 4K 15micron pixels. These arebeing purchased by ING as part of aconsortium of observatories and willbe mounted in a standard cryostatand integrated with INGs DataAcquisition System (UltraDAS) usingan SDSU-2 controller. This work willbe carried out by ING on La Palma.

The final opto-mechanical designstarted early in January and is in fullprogress with commissioning plannedfor semester 2003A. ¤

Gordon Talbot ([email protected])

A New Camera for WYFFOS

Gordon Talbot, Maarten Blanken, Romano Corradi,Begoña García (ING), Johan Pragt (ASTRON)

A utoFib2, the prime focus,multi-object spectrograph ofthe WHT, was recently

upgraded with the installation of theSmall Fibre Module. This allows toreach a fainter limiting magnitude andto observe a larger number of objectsthan with the previous large fibres.

With the new module, the image ofeach fibre (1.6 arcsec diameter in thesky) projected onto the CCD ispresently undersampled with thepresent camera of WYFFOS, theNasmyth spectrograph fed byAutoFib2. The projected full-width athalf maximum of each fibre is in fact∼ 1.4 pixels both in the spectral andspatial direction.

As part of the upgrade of theinstrument, a new camera forWYFFOS with a longer focal length(293mm instead of 132mm of thepresent camera) has therefore beendesigned. The new WYFFOS LongCamera will provide an adequatesampling of the fibres of AutoFib2,increasing the spectral resolving powerup to 9500 with the Echelle gratingpresently available with WYFFOS.

The Long Camera, in combination witha large format CCD, will also allowfurther developments, such asintroducing a larger number of fibres,or significantly increasing the spectralresolution by adopting smaller fibresin multi-object or integral-fieldspectrographs.

Beginning in the early ninetiesproposals for a new camera forWYFFOS were made by the RGO. Thecamera continued to be developed thereuntil its closure in 1998. ING then tookover project leadership and continueddeveloping the concept culminatingin 2001 in a definitive design.In 2001 the optical design andconstruction of the WYFFOS Long


2 7

Camera wascontracted toASTRON, based atDwingeloo, TheNetherlands. Justbefore lastChristmas thedesign passed the Preliminary DesignReview (PDR) held at ASTRON.

Some of the ASTRON team comeoriginally from the Kapteyn Instituteof Roden and some are relative youngdesigners who together have recentlyworked on the instruments VISIRand MIDI for the VLT and VLTI.Those from Roden have a longrelationship with ING, which isrenewed with this project.

The preliminary design was made fromZEMAX optical data and tolerancecalculations, to 3 dimensional file ofoptical lines generated by ZEMAX,copied into the drawing package pro-Engineer, into 3D dimensionalprincipal sketches of the structure inpro-E. Also 3D strength and mostlystiffness calculations where done toprove the quality.

The accompanying illustration showsthe camera (with the WYFFOS coversremoved) looking from the cryostat end.The existing Hartmann shutter fromthe original camera will be reused ina new position. Light passes througha meniscus lens and is reflected froma folding flat onto a spherical mirrorbefore passing to the detector througha cut-out in the flat. A field flattenerlens is positioned just before thecryostat window.

The meniscus lens will be made outof N-BK7 material, the diametre willbe 200mm and the original opticaldesign has been changed to usespherical surfaces, rather than theaspherical earlier design. The foldingflat is made of Zerodur about 230mmwide with a square hole in the middle.

rates and some have thermoelectriccooling and can integrate for a fewtens of seconds. A problem with manyof these products is their poor quantumefficiency of the CCDs used andrelatively high dark currents, theseshortcomings combine to make itdifficult to achieve the limitingmagnitude of the ISEC cameras~mV=20. A solution adopted at someobservatories is to use an intensifiedCCD camera, generally a MCP aheadof a cooled CCD, but we wanted toavoid this solution partly because ofthe nuisance of managing the overillumination risk, but also to offerbetter photometric performance thanthe ISEC cameras. The performancerequirements for future upgrades toING acquisition cameras hadpreviously been specified in a memo(Rutten and Barker, 1996) and theseincluded features such as on-line biassubtraction, generation of FITS filesand a minimum of 8 bit precision overthe dynamic range of the detector.These requirements were easier tomeet using commercially availablecameras aimed at the universityobservatory market. Several suppliersoffer cameras aimed at the universitytelescope niche but the MicroLuminetics Cryocam offered thepossibility of remote PC operation overa single 50 ohm coaxial cable, whilstother contenders typically neededmulticore cables of restricted lengthbetween the camera and PC. This cablelimitation was an important factor inchoosing the Cryocam although otherobservatories like the AAT havechosen to accept the cable restrictionand have mounted the controlling PCon the telescope.

The Cryocam model presentlyoperating at the Cassegrain focus of theWHT has a thinned back illuminated1k square SITe chip with 24µ pixels.Replacing the original camera with aCCD having a similar format meantthe acquisition FOV at Cassegrain hasbeen retained and slightly increased

in the y-direction, the possibility ofinterposing a focal reducer to changebetween a 1.5 arcmin and a 4 arcminFOV remains along with the originalcamera filter wheel. The chip isoperated at a temperature of 220Kand has a dark current better than0.2 e pixel1 s1 with a QE>80%between 600 to 750nm. The Cryocamwill operate in either fast readout8 bit focus mode when acquiringbright ~mV=5 7 calibrate stars ormonitoring the position of a brightsource on the ISIS slit or the normalmode with 16 bit precision. Anyshutter speed ≥ 200ms is available ineither mode giving the possibility ofconfirming the position of faint orextended objects on the ISIS slitwithout the need to trust a blindoffset. The camera is operated by theobserver from the control room andthe control and display applicationrun on a PC under the Windows 98operating system. The camera CCDdoes not operate in the frame transfermode and requires a mechanicalshutter to close during readout andthe long term reliability of thiscomponent is an area of concern,with bright stars there is a temptationto use the minimum 200ms integrationtime and a readout time of less thana second in focus mode implies severalthousand shutter operations per hour.The recommendation is that in thesecircumstances it is preferable tointegrate for longer and use a redfilter, we have however operated aCryocam at the Cassegrain focus forboth direct and slit viewing sinceMay 2001 and have not experiencedany serious problems. The sparecamera was recently tested with AF2to manually guide utilising therecently upgraded coherent guidefibres and we are considering thepurchase of enhanced Cryocamsoftware so a Cryocam can be usedfor autoguiding AF2. ¤

Clive Jackman ([email protected])


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Upgrading the WHT Acquisition TV Cameras

Clive Jackman (ING)

D espite advances in solid stateimaging devices over the lasttwenty years, the choice of a

camera to replace the aging vacuumtube devices on the WHT telescopewas not obvious. All ING telescopesoriginally had Westinghouse(Intensified Secondary ElectronConduction) ISEC TV cameras, whichcould be used at the standard25 frames1 TV rate, had an advantageof photon multiplication within anintensifier stage, and could be madeto integrate charge at the photocathode.Being able to integrate for longer thana single TV frame made these camerasattractive in astronomical applications.The integrating facility works byinhibiting the electron beam from athermionic cathode for an integernumber of TV frames before readingoff the two dimensional charge patternwith a single raster scan, the image isthen held in a digital frame store untilrefreshed by the next scan but ispresented to the observer on a TVmonitor as a stationary image duringthe interscan period. The problem withISEC cameras is that they can bedamaged by over illumination andhave poor geometric stability becauseimage distortion is dependent amongother factors on the linearity of thecamera time-base oscillators.Furthermore these cameras are nolonger supported by the manufacturerand obtaining or engineering aroundobsolete spares was starting to becomea problem. Solid-state detectors offerexcellent geometric stability are notdamaged by over illumination andhave a large dynamic range.

An important decision when retrofittingan acquisition camera to a telescopeintended to operate with a camerasuch as the Westinghouse ISEC iswhether to replace the reimagingoptics and design a system utilising asmaller format imaging device. Smallformat devices are of course cheaperand several cameras are commerciallyavailable, many work at TV frame


2 9

OTHER NEWS FROM ING

T he creation of the Isaac NewtonGroup of Telescopes, and moregenerally of the Roque de los

Muchachos Observatory, is intimatelyrelated with the relentless energy ofPaul Murdin. In October 2001, aftermany years, Paul stepped down fromthe ING Board, and this wascommemorated with a brief butinteresting workshop with the titleScience from La Palma Past,Present and Future.

Various talks were given, showing thehighlights as well as the unavoidablebut entertaining anecdotes related topast discoveries, but, more importantly,talks were also given looking at thenew developments at the observatorythat point the way to the future.

Following an introduction on theplanned developments at the ING,Carlos Frenk (Durham) beautifullyreminded the audience how keydevelopments and discoveries at theING over the past decade have helpedpoint the way towards the newgeneration of large telescopes. VilppuPiirola (Tuorla) showed how the NordicOptical Telescope exploits its excellentimage quality, while Mike Bode(Liverpool) explained that the roboticLiverpool Telescope will open a newchapter in ground-based fast responseastronomy. Michael Rowan Robinsoncomplemented Carlos Frenks talkwith examples of INGs contributionto cosmology. The two finalpresentations by Eckart Lorenz(Munich) and José Miguel RodríguezEspinosa (Tenerife), summarised thestatus of the two largest developmentsof facilities at the ORM, namely theMAGIC 17-m Cherenkov telescope,and the 10-m GRANTECAN telescope.Both these facilities will come intooperation in the near future and liftthe observatory as a whole to worldclass standards.

A Workshop in Honour of Paul Murdin

René G. M. Rutten (Director, ING)

Of course at the end there was a lighternote to thank Paul for all these yearsof hard work that have helped shapethe observatory in such a crucial way.Below, the top picture shows FranciscoSánchez presenting a gift to Paul.This celebration was a unique occasionto get four of the people togetherwho have been at the helm of theING. The picture in the middle shows,from left to right, Jasper Wall (Oxford),Paul Murdin (Cambridge), Jan Lub(Leiden) and René Rutten (ING).

The highlight of a buffet dinner inthe evening was the performance ofthe Palmeran dancing group Echentive.The bottom picture shows Carlos Frenkhaving a good time on local Palmerorhythm. This formed the close of whathad been an informative and entertainingevent with many old friends of Pauland the observatory. ¤

Other ING Publications andInformation Services

[INGNEWS] is an important source ofbreaking news concerning currentdevelopments at the ING, especially withregard to instruments.

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/science/bulletin/.

A new Technical Note has been publishedrecently: No 127 The Definition of Dark,Grey and Bright Time at ING, I. Skillen(ING), February 2002. This can bedownloaded fromhttp://www.ing.iac.es/Astronomy/

/observing/manuals/man_tn.html

Other ING publications are available on-line atthe URLs below: In-house Research Publications:http://www.ing.iac.es/Astronomy/

/science/ingpub/

Annual Reports:http://www.ing.iac.es/PR/AR/

Press Releases:http://www.ing.iac.es/PR/press/


3 0

From left to right and from top to bottom: NGC 3184, NGC 4321, NGC 3351, NGC 488, NGC 1169, NGC 3486, NGC 4254,NGC 4725 (B-band) and NGC 4579.

T he real-colour images of spiralgalaxies reproduced in thisNewsletter form part of a new

series of such pictures, currently underconstruction. The original images usedhave all been obtained with the INGtelescopes, mostly with the JKT, somewith the INT, and an occasional(H-alpha) image with the WHT. Wecollected most of the images ourselvesas part of a large PATT-supportedscience programme aimed at studying

Real-Colour Images of Spiral Galaxies

Nik Szymanek (Univ. of Hertfordshire) and Johan H. Knapen (ING and Univ. of Hertfordshire)

spiral arm structure, and the rest fromthe ING archive. For each galaxy, wehave images in the B and I bands aswell as in the near-IR Ks band (seealso article on page 3), and in H-alpha.Using a set of newly developed IRAFscripts we can produce series of imagesfor each galaxy which are registeredto a high accuracy, i.e., have the samepixel scale, orientation, resolution, andoverall image size. This is not trivial,given the use of large amounts of

archive data, taken with differentcameras, detectors and even telescopes.Whereas the data sets are beingproduced for scientific work, they serveanother purpose which is to show thebeauty and the variety of spiralgalaxies. Our sample consists of 57galaxies of all spiral types, fromflocculent (multi-armed) to grand-design (two-armed and symmetric), andwith and without bars, circumnuclearstructure, and rings.


3 1

ING Stick to the Task Work forthe NSST

Gordon Talbot, Maarten Blanken, Alan Chopping, Paul Jolleyand Juerg Rey (ING)

I NG recently demonstrated therange of services they can offerto other telescopes by completing

a contract for the Royal Academy ofSciences, Sweden for mirror handling,pad gluing and aluminising a pairof 1.4 metre diameter mirrors to beinstalled in the New Swedish SolarTelescope (NSST) on La Palma.

Mirror handling involved the need toinvert the mirrors after unpacking,then placing them face down so thata set of eighteen Invar axial pads couldbe glued to the rear of each one. Thisinvolved rehearsing the procedure withthe dummy mirror supplied whichmatched the size and weight of theactual mirrors (1400mm diameter,150mm thick and 600Kg). Rehearsalof these operations is vital to avoidunforeseen occurrences that coulddamage optical components; the moreso when they are this size and weight.INGs policy for all of this type ofwork is that we look after the mirrorsas if they were our own.

Once the mirrors were in position thetemplate that defined the position ofthe axial pads on the back of eachmirror was aligned. The mirror surface

was prepared by carefully cleaningthen grinding the Zerodur in the areaof each pad before applying a specialprimer. The surfaces of the axial padswere roughened. The pads were thenpositioned and aligned using the jigssupplied, before being attached by thespecified two-pack flexible epoxyadhesive. The jigs controlled thethickness of the epoxy under each axialpad to 75 microns. One mirror wascompleted before the template and jigswere transferred to the second mirror.

The work was carried out in the WHTaluminising area. To cure the adhesive,they had to be kept at an elevatedtemperature of at least 24 degrees Cfor seven days. To achieve this a tentwas created for each mirror usingpolythene sheeting and scaffolding,which was then warmed with spaceheaters to reach the requiredtemperature while minimising thetransfer of additional heat to the dome.

While the axial pads were being gluedto the mirrors a total of three testpieces (one for each day of gluing)were made using some of the actualepoxy mixes used. The test pieces wereaxial pads glued to steel plates, which

To produce the real-colour images, theimage sets, originally in FITS format,are read into an image processingpackage called Maxim DL. Thisprogramme allows manipulation ofING images as well as powerful imageco-addition, calibration and colourcombination/balancing routines.Images are saved in a variety offormats including FITS, TIFF andJPEG. It is our intent to produce afinished result that extracts detail fromthe core region of galaxies as well asany other features, such as rings,gravitational tails, interacting arms,etc. A variety of processing routineswill do this successfully, such aslogarithmic scaling, but in our opinionthe best routine is that of DigitalDevelopment a software algorithmcreated by the Japanese amateurastronomer Dr. Kunihiko Okano.Digital Development applies ahyperbolic transfer function that sitsneatly between the standard gammacurve and a logarithmic curve. TheDigital Development curve is successfulfor a number of reasons. The steeplyrising curve withholds the brightnessvalue of the sky background and asthe curve levels out the effect is toenhance the middle-grey tones,typically information which iscontained in the overexposed (burnt-out) core of the galaxy. As the curvefinally levels out and flattens this hasthe effect of compressing the dynamicrange of the image. A sharpeningroutine known as unsharp maskingis also applied to enhance detail. Thereare several user-definable parameterswithin Maxim DL, as well as a previewscreen which displays how the imagewill appear once Digital Developmentis applied.

Each of the galaxy image componentswill be processed using the abovemethod. Best (or certainly mostspectacular) images are achieved usingstandard B, R and V images. Additionalwavelength data, such as H-alphacomponents, can be overlaid at anypoint. Maxim DL allows the colouraddition and registration of theindividual files but, in our opinion, thebest results are obtained usingpowerful image-manipulation softwaresuch as Adobe Photoshop. The FITSfiles are converted to 8-bit TIFF files

after careful scaling, and combined inregistration. Further processing suchas colour balancing and the removalof unsightly artifacts such as cosmicray hits, dust-donuts and generalCCD defects are easily appliedin Photoshop.

It is important to realise that theabove processing routines are appliedto produce aesthetically pleasingimages and perhaps not images thatare intended for purely scientificresearch. To be fair, the DigitalDevelopment routine extracts moredetail than most other applicationsand performs spectacularly with the

nuclei of galaxies and globular clusters.The ING Archive contains manyhigh-quality images taken with theJKT, INT and WHT and these imagescan be used to demonstrate the qualityof ING equipment and, indeed, thequality of the sky at La Palma (seeSky & Telescope, June 2001, pp. 4445).

We thank Sharon Stedman, DanBramich, Stuart Folkes and JavierMéndez for their help in theobservations and data reductionand handling. ¤

Nik Szymanek ([email protected])


3 2

had had exactly the same surfacetreatment as the actual pads andmirrors. These were left to curealongside the mirrors. After the curingtime each test piece was then subjectedto a pull-off test. Each test piece wassandwiched between thick steel platesto avoid local distortions. A weighingdevice was slung from the lifting crane.To this was attached a sling with thetest piece shackled underneath, andtest weights were progressively added.All three demonstrated they wouldwithstand the specified 100Kg load.

The mirrors complete with firmlyattached axial pads were then turnedright side up, before being preparedthen coated together in the WHTaluminising plant.

After coating, but while still in thealuminising area, the mirrors werethen installed in their cells byNSST staff, then with assistance fromING transported to the telescopefor installation.

A large number of ING staffcontributed a wide range of skills tothis work, principally members of theMechanical, Site Services and

Telescope Operators Groups. Somestages of the work required relativelylarge numbers of people present, forinstance the mirror handling requiredat least five to co-ordinate all theactions of lifting and rotatingthe mirror.

The NSST representatives also assistedand of course made the whole thingpossible by first of all entrusting theirmirrors to ING and with their detailwork in the design of the pads,templates and jigs.

Due to the current economic climateING will be driven in the future toseek to carry out more repaymentservices in areas where we have specialexpertise or facilities, with the aim ofretaining a wide skills base, whilemaintaining both our proficiency andfacilities by exercising them. Theseareas extend beyond aluminising whichhas been the main service in the past,to other areas, (which will includeoptical fibres) where ING have builtup experience from our operationsand projects. ¤

Gordon Talbot ([email protected])

A Euroconference Organised by the ING: Symbiotic StarsProbing Stellar Evolution, La Palma, 2731 May 2002

Romano L. M. Corradi (ING)

interactions of detached or semi-detached binary stars. They are alsoamong the (intrinsically) brighteststars, which makes them excellentobservational targets both in ourGalaxy and in nearby galaxies.

Mass accretion onto the hot componentplays a fundamental role indetermining the properties andevolution of symbiotic stars, andinvolves energetic phenomena relevantto many other astrophysical fields. Thehot component of the vast majority ofsymbiotic systems is in fact a luminous(~1,000 solar luminosities) and hot(100,000 K) white dwarf powered bythermonuclear burning of the materialaccreted from its companions wind.

H alf or maybe two thirds ofstars in the Universe arebinaries. Among them,

symbiotic stars are long-periodinteracting binaries composed of anevolved giant primary and a hot andluminous companion surrounded byan ionised nebula.There are twodistinct classes of symbiotic stars: onecontaining normal red giants andhaving orbital periods of about 115years, and the other with Miraprimaries usually surrounded by awarm dust shell, and orbital periodsgenerally longer than 10 years.Symbiotic stars are thus the interactingbinaries with the largest orbitalseparations, and their study is essentialto understand the evolution and

Depending on the accretion rate, thesesystems can be either in a steadyburning configuration or undergohydrogen shell flashes, which in manycases last for decades due to the lowmass of the white dwarf. In addition,in many systems the hot componentshows activity on time scales of a fewyears that cannot be simply accountedfor by the thermonuclear models.Possible and promising explanationsof this activity involve changes inmass transfer and /or accretioninstabilities in a disk.

From top to bottom: one of the NSSTmirror blanks in the aluminising area atthe WHT, pad gluing in the rear of one ofthe blanks and the two mirrorsassembled on top of the NSST tower.


3 3

Surrounding the interacting stars, arich and luminous circumstellarenvironment is found, which is theresult of the presence of both anevolved giant with a heavy mass lossand of a hot companion copious inionising photons and often producingits own wind. In particular, stronglydifferent environments are expected,such as ionised and neutral regions,dust forming regions, accretion/excretion disks, interacting winds,bipolar outflows and jets. The bestknown, spectacular example of aionised nebula around a symbioticstars is very likely the SouthernCrab (Henize 2104), whose innerregion is displayed in the conferenceposter shown in the figure. Such acomplex multi-component structuremakes symbiotic stars a veryattractive laboratory to study manyaspects of stellar evolution in low-massbinary systems.

For these reasons, a EuroConferencewith the title Symbiotic stars probingstellar evolution was organised bythe ING on La Palma from May 27 to31, 2002. Financial support to theconference was provided by the INGand the European Commission, High-Level Scientific conferences. The mainscientific goal of the conference wasto bring together the leading scientistsin the world to revise thoroughly thecurrent state of our knowledge in thisfield. This attracted to La Palma onehundred astronomers from thirtydifferent countries who set, for thefirst time, firm links between symbioticstars and related objects, helping tounderstand for instance the role ofsuch interacting binaries in theformation of stellar jets, planetarynebulae, novae, supersoft X-raysources, and SNIa. Many of them areissues concerning the late stages ofstellar evolution of which at presentlittle is known, but with importantimplications for our understanding ofthe stellar populations and chemicalevolution of galaxies, as well of theextragalactic distance scale.

So far, most of the research in thefield of symbiotic stars has beenconducted by European astronomers,spread among almost every Europeancountry. Therefore this Euroconferencewas also the occasion to strengthen

the links and collaborations betweenresearchers from different Europeaninstitutions. Moreover, more than 50young researchers and PhD students(especially European) were able toattend the conference thanks to theEU and ING funds. The event was aunique experience for many of them,in which they found guidelines andsuggestions to direct their futureresearch toward important issues inmodern astrophysics. Special trainingsessions entirely dedicated to theseyoung researchers were organisedwith this aim.The list of invited speakers included:B. Balick (USA), M. Bode (UK), R.

Corradi (UK), I. Iben (USA), A. Jorissen(Belgium), J. Mikolajewska (Poland),U. Munari (Italy), H. Nussbaumer(Switzerland), H. M. Schmid(Switzerland), H. Schwarz (Chile),E. Sion (USA), N. Soker (Israel), J.Sokoloski (USA), T. Tomov (Poland),and P. Whitelock (South Africa).

For more information about theconference, visit our web site athttp://www.ing.iac.es/

/conferences/symbiotics/. ¤

Romano Corradi ([email protected]),Chair of LOC and SOC


3 4

News from the Roque

A lthough for astronomical observations the weather last winter hasbeen rather poor, this has not hampered fast progress in theconstruction of the various new facilities, which also continued over

the summer. The dome and annex building of the 10-m GTC have maderemarkable progress. The dome is nearly fully completed at the time ofwriting. The dome of this grand facility is now fully silhouetted against thehorizon when seen from the ING telescopes site.

The construction of the MAGIC Cherenkov telescope has also been remarkablyspeedy. The open, unprotected telescope structure was erected in only a fewweeks and will soon receive the mirror surface elements. This will most definitelyadd a bright sparkle to its appearance under the Canarian sunshine. You cantmiss it when driving up from the Residencia!

Also the Liverpool Robotic Telescope is making good progress. Followingcompletion of the ground works and foundations, the dome work is now at avery advanced stage. The telescope structure will be erected soon.

Maybe less noticeable but not less impressive are the developments in theSwedish Solar Telescope, where the original telescope has now been replacedby a new telescope within the existing tower. The new telescopes optics, witha 97 cm entrance pupil, is twice the size of the old telescope.

Looking towards the future potential of the ORM site, a site testing tower forsolar observations has been erected not far from the WHT. This tower holds asolar DIMM (Differential Image Motion Monitor) and is operated by NOAO insupport of a general site testing campaign for a future large solar telescope.

Also in the future plans for an extremely large telescope exist for the ORM.The EURO-50 project, proposing a 50-m optical/IR telescope, is one of severalprojects that are being studied world-wide. The artists impression below showsthe scale of such an installation in comparison with other facilites on site.

For readers who would like to see progress on some of these facilities forthemselves, see the various live web cameras:

GTC: http://www.gtc.iac.es/webcam_s.aspMAGIC: http://mc5rq.hegra.iac.es/view/view.shtmlLiverpool Telescope: http://telescope.livjm.ac.uk/Webcam/ ¤

Haloes of Planetary Nebulae from the INT WFC. The images of the three planetary nebulae displayed on the followingpage were obtained by Romano Corradi at the INT with the Wide Field Camera, that covers a field of view of 34×34 arcmin. They

are very deep exposures (one to three hours exposure time) obtained through an Hα +[NII] narrow-band filter, and were aimedat studying the faint haloes that are known to surround a large fraction of planetary nebulae. We believe that these haloes are

the trace of the last episodes of mass loss from the stellar progenitors of the nebulae, occurred a few 104 years ago when theywere in the pulsating red-giant phase that eventually leads to the complete ejection of the stellar envelope and the formation ofa planetary nebula. In the case of two of the nebulae (Sh 2200 and NGC 3242) displayed in the figure, however, the extended

and structured emission revealed by the WFC images might not be material lost by the stars in the recent past, but simplyinterstellar gas located in the proximity of the planetary nebulae and ionized by the energetic radiation from their central stars.¤

Planetary NebulaNGC 3242

Helix Planetary NebulaNGC 7293

Planetary NebulaSh 2 200


3 6

The ING PR Collections of Images

One of the best ways to advertise the observatory to the public is by showingsuperb astronomical images obtained at the telescopes. For this reason atING we have started to collect astonishing images of celestial objects whichare then made available on the web. Full credit is given to the observers andthe authors of the images.

The images are offered as part of several collections which can be found athttp://www.ing.iac.es/PR/images_index.html. Here you will alsofind information on how to participate in this exciting project.

On the following page we show a recent image of M42 and M43 obtainedusing the Wide Field Camera on the INT. Such an image is already part ofour PR collections of images. Credit: Simon Tulloch (ING) and Nik Szymanek(Univ. of Hertfordshire).

Javier Méndez ( [email protected])

Seminars Given at INGVisiting observers are politely invited to givea seminar at ING. Talks usually take place inthe sea level office in the afternoon and lastfor about 30 minutes plus time for questionsafterwards. Astronomers from ING and otherinstitutions on site are invited to assist. Pleasecontact Francisco Prada([email protected])and visit this web page:http://www.ing.iac.es/Astronomy/

science/seminars.html, for more details.These were the seminars given in the last sixmonths:

30 August. The exceptional Dwarf Nova, V485 Cen,Hannah Worters (Univ. of Sheffield & ING)

30 August. Star formation in spiral galaxies,Stuart Folkes (Univ. of Hertfordshire & ING)

27 August. Planetary Exospheres, CesareBarbieri (Padova)

26 August. A study of B-type line-profilevariables in close binaries, KatrienUytterhoeven (Leuven/Mercator Telescope)

12 August. AGN-selected clusters as revealed byweak lensing, Margrethe Wold (IPAC, USA)

7 August. Dynamical Processes in the CentralKpc and AGN, Isaac Shlosman (JILA & Univ.Kentucky, USA)

30 July. Lucky exposures: diffraction limitedCCD imaging, Bob Tubbs (IoA Cambridge)

18 July. Red Giants in the Magellanic Clouds,Maria Rosa Cioni (ESO, Germany)

4 July. AstroGrid: Creating the UK's VirtualObservatory, Nic Walton (IoA Cambridge)

3 June. TASCA: the Tololo All-Sky CAmera,Hugo Schwarz (CTIO)

24 May. The EURO-50 project: The worlds largesttelescope at the ORM, René Rutten (ING)

21 May. Double Bars, Inner Disks, and FossilNuclear Rings: The Strange and ComplexInteriors of Barred Galaxies, Peter Erwin (IAC)

16 May. The surface of icy minor planets: trans-neptunian objects, Centaurs, comet nuclei, andtrojan asteroids, Javier Licandro (CGG & TNG)

23 April. Binary subdwarf-B stars and theorigin of Extreme Horizontal Branch stars,Pierre Maxted (Keele Univ.)

25 March. Adaptive optics developments onMauna Kea, Hawaii, Chris Benn (ING)

21 March. Lyman-break galaxies: Are theyforming bulges? Sam Rix (IoA Cambridge)

Recent Visits of VIPsIn the last few months ING has received several visits of VIPs: the SpanishScience and Technology Minister, the British Embassador in Madrid, theIndustry, Trade, Research and Energy Commission of the EU, the Scienceand Technology Commission of the Spanish Senate, the Science andTechnology Research Committee of the EU (CREST), the Joint ResearchCentre of the European Commission (JRC) and some ESO representativesinvolved in the construction of the OWL telescope. In the accompanyingphoto we can see the representatives of the Industry, Trade, Research andEnergy Commission of the EU in the WHT.

Personnel MovementsAfter many years at ING Nic Walton returned to the UK, to the Institute of Astronomy inCambridge, where he is involved in the AstroGrid developments. Nic has been at the heart ofvarious developments at the observatory, from which astronomers continue to profit. Grateful forhis efforts, we wish him well in his new career.

Paul Morrall, who worked in the mechanical section for a number of years, also returned to theUK. He now employs his skills in the field of physics at Daresburry Laboratory.

Thomas Augusteijn decided to take up a position as Astronomer in Charge at the Nordic OpticalTelescope. Although it is sad to see him leaving ING, it is good that his skills and extensiveexperience in the observatory business have been retained at the ORM.

INGs second EU-funded Mary Curie Fellow has strengthened our adaptive optics team: SebastianEls, previously at the University of Heidelberg, arrived in La Palma earlier in the year.

Arami Felipe and María Batista have left the administration group recently to find fortuneelsewhere.

Francisco Prada and Javier Licandro have taken up positions as support astronomers.

Chris Evans arrived at ING on a PDRA position to work with Danny Lennon on massive stars.

As part of the financial cutbacks, unfortunately many familiar faces will not be seen at theobservatory anymore. I mention Manuel Acosta, Cecilio Alvarez, Sheila Crosby, InocencioGarcía, Mavi Hernández, John Mills, Peter Moore, and Carlos Ramón who have all left inrecent months. Between them, there are many decades of effort dedicated to the ING telescopes,some going back to the very early days of the construction of the observatory, when neither roadsnor Residencia, or even the WHT existed ! We wish them all well for the future.


3 8

TELESCOPE TIME

A New Definition of Dark, Grey and Bright Time at ING

Ian Skillen (ING)

T he legacy method used todefine dark, grey and brighttime at ING is based on the

fraction of the night for which theMoon is below the horizon. Althoughthis is perfectly adequate forcharacterising dark time, it is less sofor characterising grey and brighttime. As the Moon ages the focusshould change to quantifying theenhanced sky surface brightness fromscattered moonlight.

The optical sky surface brightness ofthe moonlit sky in some line-of-sightdepends primarily on the FractionalLunar Illumination, FLI, followed insignificance by the angular separationbetween the line-of-sight and theMoon, and by the altitude of theMoon. The FLI is given to a goodapproximation by

2×FLI =1 cosβ cos(λλ )

where λ, λ are the longitudes of theMoon and Sun respectively, and β isthe latitude of the Moon. Partitioninga lunation by the fraction of each nightfor which the Moon is below the horizoncorrelates strongly with partitioningthe Moons longitude, since |β| 5.3°,but ignores the change in longitude ofthe Sun by ~1° per day, and thereforedoes not give a consistent mappingonto FLI. As a result of this and thenon-uniform motion of the Moon inits orbit, the FLI on, for example, thefirst and last bright nights in a givenlunation can be as small as 0.45 andas large as 0.80. The difference in FLIon first and last bright nights exceeds0.20 in ∼ 30% of lunations, and exceeds0.30 in ∼ 5% of lunations. An importantconsequence of this is that the skysurface brightness on first and lastbright nights can differ by as much as∼ 1.2 mag/arcsec 2 with the Moon beingpresent in the sky for the same fraction

of each night. Furthermore, in suchasymmetric lunations the skybrightness in the moonlit part of greynights can be up to ∼ 1 mag/arcsec2

brighter than in the moonlit part ofthe darkest bright night in the samelunation.

Inconsistent partitioning of lunationscan lead to a mis-match betweenobserving programme requirementsand actual conditions. A programmeallocated, for example, a specific grey-time award, based on some assumedtypical grey-time sky background, canbe scheduled in significantly brighterconditions, and vice versa, and this isdetrimental to observing efficiency.These considerations prompted areappraisal of the legacy method, andthe derivation of a better alternativeto it.

Sky Surface Brightness

The direct way to partition classically-scheduled time is in terms of the skysurface brightness itself, since it isthis which impacts the signal-to-noiseratios for observations of a givenintegration time. The main contributorsto the moonless sky optical surfacebrightness in a line-of-sight and in aspecific bandpass are airglow, thezodiacal light and starlight. Benn andEllison (1998) find the high galacticlatitude, high ecliptic latitude, zenithVsky brightness at solar minimum atthe ORM to be Vsky=21.9mag/arcsec2.The sky is brighter at low latitudesby ∼ 0.4 mag/arcsec 2, and at higherairmasses by ∼ 0.3 mag /arcsec 2 (atX ∼ 1.5), and because of variable solaractivity, the airglow component isbrighter by ∼ 0.4 mag/arcsec2 at solarmaximum. There is no dependence onextinction, AV , for AV < 0.25mag/airmass.

The contribution to the sky surfacebrightness from scattered moonlightwhen FLI 0.15 exceeds the spatialvariations from airglow, zodiacal lightand starlight, and so to partitionclassically-scheduled telescope time itis sufficient to partition by theilluminated fraction of the Moons disc,acting as a proxy for the sky surfacebrightness from scattered moonlight.

Two scattering mechanisms dominatethe background from moonlight; Miescattering by aerosols and Rayleighscattering by molecules. Mie scatteringis highly forward, and so Rayleighscattering dominates for scatteringangles (i.e. angular distances fromthe Moon) 90°. Krisciunas &Schaefer (1991) derived scatteringformulae to compute the contributionof moonlight to the sky backgroundat some airmass as a function of lunarphase, lunar zenith distance, distancefrom the Moon and extinction. Theuncertainty in these formulae isestimated to be ∼ 0.25mag/arcsec2;local prevailing conditions such asenhanced levels of atmospheric dustwill of course reduce their precision.

The mean ∆VMoon from theVsky = 21.9 mag/arcsec2 dark sky iscomputed from these formulae for theMoon at a zenith distance of 60° (sothat scattering angles of up to 120°are accommodated at airmasses ≤ 2),as a function of FLI in increments of0.1, and at scattering angles rangingfrom 30° to 120° in increments of 5°,measured both in the azimuthaldirection and in altitude (see Figure 1).The computed differences in bothdirections at a given scattering angleare only a few per cent. Thesecalculations have been normalised toJKT observations of the moonlit sky,made by Chris Benn on dust-freenights in 1998. The effect of decreasing

O.

<∼

>∼

>∼

O.

the Moons zenith distance on ∆VMoonat a given angular distance from it issmall, 0.1 magnitude, i.e roughlythe same size as the points in Figure 1.∆VMoon does however fall off rapidlyby ~1magnitude /arcsec 2 when theMoon is low on the horizon. Therefore,Figure 1 forms a consistent basis forquantifying the effects of moonlighton the sky background at specificscattering angles from the Moon.

Several aspects of this Figure arenoteworthy. As the scattering angleincreases, the contribution of scatteredmoonlight to the sky surface brightnessdecreases up to ∼ 90°, and then beginsto increase again when Rayleighscattering dominates. Therefore, in thepresence of moonlight, a good strategyfor optical observations is to observein a broad annulus centred ∼ 90° fromthe Moon whenever possible, in orderto minimise the effects of scatteredmoonlight.

The gradient of scattered moonlightis remarkably flat at scattering angles∼ 90°. In fact, even at full Moon, therange in scattered moonlight within70°110° of the Moon is ∆VMoon ±0.1.Therefore, it is sensible to quantify thecontribution of scattered moonlight tothe sky surface brightness in terms of∆VMoon computed ∼ 90° from the Moon.

The FLI assumes greater importancein determining the sky surfacebrightness than angular distance fromthe Moon, for Moon separations 50°.The change in FLI is ∼ 0.1 per day inthe neighbourhood of quadratures,and therefore this emphasises theimportance of having consistentpartitions into grey and brightcategories; inconsistent partitions arein general not compensated for by thedistribution of targets on the sky inrelation to the Moon.

The sky brightness approaching fullMoon, i.e. zero lunar phase angle,increases strongly due to the oppositioneffect, which arises from a combinationof shadow-hiding (the shadows of lunarparticles are occulted by the particlesthemselves) and coherentbackscattering (multiple scatteringof sunlight off lunar dust grains,

predominantly in the backwarddirection to the incident sunlight).

Dark, Grey and Bright Time

The definition of grey and brightthresholds is to some extent arbitrary.What is important is that the definitionis both sensible and consistent, andthat it is understood and agreed byapplicants and TACs, and adhered toin the scheduling process. Consistencyin terms of sky surface brightness isachieved by partitioning on thefractional lunar illumination, actingas a proxy for sky surface brightness90° distant from the Moon. In termsof sensibleness, the numbers of nightsin each category should not be greatlydifferent from the legacy method, buta small increase in the number of greynights, at the expense of bright nights,is desirable to better match demand.

Averaged over a Saros cycle ( ∼ 37semesters), the same number of dark

nights (9.6), 0.7 additional grey nights(7.9) and 0.7 fewer bright nights (12.0)per lunation result from the adoptedpartitioning scheme:

Dark: 0.00 ≤ FLI < 0.25Grey: 0.25 ≤ FLI < 0.65Bright: 0.65 ≤ FLI ≤ 1.00

where the FLI is computed for 0h UT.Illuminated fraction changes by∼ 0.1 per day in the region of thesethresholds, and this resolution effectmeans that inconsistencies in theFLI are constrained to be 0.1 at thedark/grey and grey/bright boundaries.

For a given FLI, the fraction of thenight for which the Moon is in the skycan vary by as much as ∼ 25%, for thesame reasons that the fraction of thenight which is moonless does notconsistently estimate the FLI. Forexample, at FLI=0.65 the Moon canbe in the sky for between ∼ 65% and∼ 90% of astronomical darkness. This


3 9

Figure 1. The brightening of the dark sky (Vsky=21.9 mag/arcsec2, corresponding tolow airmass, high ecliptic and galactic latitude, and solar minimum) by scatteredmoonlight, calculated as a function of fractional lunar illumination and angular distancefrom the Moon.

>∼

<∼

<∼

<∼

could be taken into account for eachnight by scaling the moonlit sky surfacebrightness by this fraction to give aweighted background for the night,but on balance it is considered better topartition telescope time solely in termsof the worst case sky surface brightnesscomputed ∼ 90° from the Moon.

The predicted ranges in the zenith Vsky surface brightness at high galacticand ecliptic latitudes, and solarminimum, and at an angular distancefrom the Moon of ∼ 90°, are 21.2 21.9 mag/arcsec 2 for dark time, and19.9 21.2 and 18.019.9 mag/arcsec2

respectively for the moonlit parts ofgrey and bright time. For the meansky, i.e. over all latitudes ∼ 90°from the Moon, these ranges are∼ 0.5mag/arcsec 2 brighter because ofthe larger contributions of airglow,zodiacal light and starlight.

This definition of dark, grey and brighttime will be used in constructing theING schedules from Semester 2002Bonward. The exposure time calculator,

SIGNAL, has been modified to offer anoption specifying typical sky surfacebrightnesses for dark, grey and brighttime, corresponding to Vsky=21.50, 19.75and 18.5 0 mag/arcsec2 respectively.

A longer version of this article isavailable as ING Technical NoteNo. 127, available at URLhttp://www.ing.iac.es/Astronomy/

/observing/manuals/man_tn.html

Acknowledgements

It is a pleasure to acknowledgediscussions with Thomas Augusteijn,Steve Bell and Rob Jeffries. ¤

References:

Benn, C. R. & Ellison, S. L., 1998, INGTech. Note, 115.

Krisciunas, K. & Schaefer, B. E., 1991,PASP, 103, 1033.

Ian Skillen ([email protected])


4 0

Important Dates

Deadlines for submittingapplications

UK PATT:

15 March, 15 September

NL NFRA PC:

31 March, 30 September

SP CAT: 1 April, 1 October

ITP: 30 June

Semesters

Semester A: 1 February 31 July

Semester B: 1 August 31 January

Telescope Time Awards Semester 2002A

For observing schedules please visit this web page:http://lpss33.ing.iac.es:8080/cgi-bin/schedules.pl

ITP Programmes on the ING Telescopes

Doressoundiram (Paris), Multi-color taxonomy of trans-Neptunian objects.ITP/2002/1

Ruiz-Lapuente (Barcelona), Supernova and the physics of supernovaexplosions. ITP/2002/4

William Herschel Telescope

UK PATT

Axon (Hertfordshire), The Black Hole Mass-Velocity Dispersion Correlation.W/2002A/38

Barcons (IF Cantabria), An XMM-Newton international survey (AXIS-II):unveiling the hard X-ray source populations. ITP/2001/2 PB

Barnes (St Andrews), Starspot tracking on the W Ursae Majoris system BWDra. W/2002A/41

Benn, (ING), Adaptive-optics imaging of QSO host galaxies. W/2002A/6 Bower (Durham), The Sauron Deep Survey. W/2002A/50 Boyce (Bristol), K-band imaging of gas-rich low surface brightness galaxies

found at 21cm. W/2002A/52 Coggins (Nottingham), Mapping Elliptical Galaxy Mass Distributions using

Gravitational Redshift. W/2002A/35 Davies (Durham), Mapping Early Type Galaxies along the Hubble Sequence.

W/2002A/21 Dhillon (Sheffield), Coordinated optical and X-ray observations of the eclipsing

polar HU Aqr. W/2002A/9 Fitzsimmons (Belfast), The Size Distribution and Colours of Short-Period

Comets. W/2002A/67 Gledhill (Hertfordshire), AO imaging of post-AGB circumstellar envelopes.

W/2002A/11 Gray (Edinburgh), Combined X-ray and weak lensing mass profiles of the

brightest cluster lenses. W/2002A/80

Jeffries (Keele), Low mass stellar populations in the most massive OB associations.W/2002A/72

Kleyna (IoA,Cambridge), Dark matter in the UMi dwarf spheroidal. W/2002A/46 Kodama (Tokyo), History of Galaxy Mass Assembly in the Hierarchical

Universe at z ∼ 1. W/2002A/58 Marsh (Southampton), Magnetic braking and solar cycles in detached binary

stars. W/2002A/7 McMahon (IoA, Cambridge), Constraining the contribution to the UV background

from z = 3 and z =5 quasars. W/2002A/78 Meikle (Imperial College), Detection and Study of Supernovae in Nuclear

Starburst Regions. W/2001B/34 (Long term) Meikle (Imperial College), Detailed study of the physics of nearby Type Ia

Supernovae. W/2002A/49 Merrifield (Nottingham), Determining the Dynamics of Round Elliptical

Galaxies. W/2002A/20 Miller (Oxford University), A Survey for wide-separation gravitational lenses

from the 2dF QSO Redshift Survey. W/2002A/33 Page (Mullard Space Science Lab/UCL), Optical identification of faint X-ray

sources in a deep XMM-Newton/Chandra survey. W/2002A/43 Peroux (IoA, Cambridge), Tracing Galactic Haloes at 3.0< z < 4.5 using CIV

Absorption. W/2002A/14 Pettini (IoA, Cambridge), CORALS II: Assessing the Dust Bias in Damped

Lyman-α Systems at Intermediate Redshifts. W/2002A/10 Rolfe (Leicester), The Orbital Velocities and Stellar Masses in the Dwarf

Nova IY UMa. W/2002A/28 Ryan (Open University), Carbon nucleosynthesis in the first stars. W/2002A/1 Shanks (Durham), A 2dF QSO Lensing Estimate of Ω m via Faint QSO

Number Counts. W/2002A/76 Smail (Durham), Testing Photometric Redshifts using Cluster Lenses. W/2002A/5 Smith (Durham), Probing the Formation Epoch of Massive Elliptical Galaxies.

W/2002A/56 Steeghs (Southampton), The structure of AM CVn binaries and their discs.

W/2002A/31 Tanvir (Hertfordshire), Rapid imaging of GRB error boxes and spectroscopy

of GRB-related optical/IR transients. W/2002A/65 Unda Sanzana (Southampton), A new structure on U Gem? W/2002A/51


4 1

NL NFRA PC

Förster Schreiber (Leiden), Near-infrared Snapshot Survey for Bright LensedRed High-redshift Galaxies. w02an002

Groot (Nijmegen), Spectroscopic Identification of Old White Dwarf Candidatesin the Faint Sky Variability Survey. w02an001

Habing (Leiden), Asymptotic Giant Branch stars in northern Local Groupgalaxies. w02an003

Kuijken (Groningen), Determining the Dynamics of Round Elliptical GalaxiesUsing the Planetary Nebula Spectrograph. w02an005

Romanowsky (Groningen), Globular Cluster Kinematics at Large Radii in M49.w02an006

Salamanca (Amsterdam), Rapid imaging of GRB error boxes and spectroscopyof GRB-related optical/IR transients. w02an008

de Zeeuw (Leiden), Mapping Early-Type Galaxies along the Hubble Sequence.w02an007

SP CAT

Balcells (IAC), Estudio de galaxias con formación estelar extrema a altocorrimiento al rojo. W23/2002A

Battaner (Granada), Rotación del sistema estelar en la periferia de galaxiasespirales. W6/2002A

Béjar (IAC), La función de masas subestelar en Orión y Praesepe. W28/2002A Cairós (IAC), Multiwavelength studies of metal-poor Blue Compact Dwarf

Galaxies. W4/2002A Carrera (IAC), Determinación de la relación en cúmulos globulares en

destrucción por marea. W26/2002A Casares (IAC), Optical reprocessing lines as tracers of companion stars in

LMXBs. W19/2002A Castro-Tirado (IAA-CSIC, LAEFF), La naturaleza de las explosiones cósmicas

de rayos gamma GRBs. W27/2002A Colina (IF Cantabria), Integral field spectroscopy of ultraluminous infrared

galaxies. W1/2002A Manchado (IAC), Near infrared imaging of galaxy fields. W21/2002A Martínez-Delgado (IAC), Destrucción de galaxias enanas en el halo Galactico:

cinemática de la corriente Norte de Sagitario. W25/2002A Mediavilla (IAC), Curvas de extinción en galaxias con redshift intermedios.

W20/2002A Pérez (Madrid Complutense), Spatial analysis of populations in local star-

forming galaxies. W5/2002A Rebolo (IAC), Did very massive stars produce r-elements? W11/2002A Rebolo (IAC), JOVIAN: detección directa de planetas gigantes alrededor de

estrellas y aislados. W32/2002B [sic] Ruiz-Lapuente (Barcelona), Estrellas compañeras de supernovas. W14/2002A Ruiz-Lapuente (Barcelona), Supernovas a z = 0.35. W15/2002A

INSTRUMENT BUILDERS GUARANTEED TIME

Packham (Florida), The initial conditions to star formation. GT/2002A/1

Isaac Newton Telescope

UK PATT

Boyce (Bristol), CCD imaging of gas-rich low surface brightness galaxiesfound at 21cm. I/2002A/15

Feltzing (Lund Observatory), Metallicity distribution functions in LocalGroup dwarf spheroidal galaxies. I/2002A/18

Fitzsimmons (Belfast), Rapid-response astrometry of potentially hazardousasteroids. I/2002A/26

Gilmore (IoA, Cambridge), Eclipsing K/M Dwarfs and the Low-Mass StellarM/L Ratio. I/2002A/20

Hilditch (St. Andrews), Accretion Hot Spots in Near-Contact Binaries. I/2002A/13 James (Liverpool), Star formation in the local Universe: Hα imaging of the

Virgo cluster. I/2002A/25 Jameson (Leicester), Rigorous limits on the bottom end of the Coma open

cluster mass-function. I/2002A/29 Jeffries (Keele), Low mass stellar populations in the most massive OB

associations. I/2002A/32 Marsh (Southampton), Subdwarf-B stars: tracers of binary evolution.

I/2002A/4 Meikle (Imperial College), Detailed study of the physics of nearby Type Ia

Supernovae. I/2002A/14 Oliver (Sussex), The INT SIRTF-Legacy: Extra-galactic Survey (ISLES).

I/2002A/40 Tanvir (Hertfordshire), Rapid imaging of GRB error boxes and spectroscopy

of GRB-related optical/IR transients. I/2002A/27

NL NFRA PC

Beijersbergen (Groningen), UBR imaging of the Coma cluster periphery.i02an003

Kuijken (Groningen), Sloan standard fields for the photometric calibration ofOmegaCAM images. i02an002

Mack (ASTRON/NFRA), Constraining the BL Lac Luminosity Function. i02an001 Salamanca (Amsterdam), Rapid imaging of GRB error boxes and spectroscopy

of GRB-related optical/IR transients. w02an008 [sic]

UK/NL WFS Programmes

Dalton (Oxford), The Oxford Deep WFC Survey. WFS/2002A/6 Davies (Cardiff ), Multi-coloured large area survey of the Virgo cluster.

WFS/2002A/2 van den Heuvel (Amsterdam), The Faint Sky Variability Survey II. WFS/2002A/1 McMahon (IoA), The INT Wide Angle Survey. WFS/2002A/8 Walton (ING), The Local Group Census. WFS/2002A/4 Watson (Leicester), An Imaging Programme for the XMM-Newton Serendipitous

X-ray Sky Survey. WFS/2002A/3

SP CAT

Balcells (IAC), Estudio de Galaxias con Formación Estelar Extrema a AltoCorrimiento al Rojo. I8/2002A

Casares (IAC), Curva de velocidad radial y función de masa del microcuasarLS5039. I5/2002A

Castro-Tirado (IAA-CSIC, LAEFF), La naturaleza de las explosiones cósmicasde rayos gamma GRBs. W27/2002A

Deeg (IAC), Sample Definition for Exoplanet detection by the COROT SpaceCraft.I10/2002A

Herrero (IAC), Espectroscopía cuantitativa de estrellas O ionizantes. I11/2002A Herrero (IAC), Preparándose para OSIRIS: población estelar joven de NGC

6946. I20/2002B [sic] Hidalgo (IAC), Estructuras a gran escala en galaxias irregulares. I19/2002B [sic] Lázaro (IAC), Fotometría infrarroja de sistemas Algol. I14/2002A López (Basel), Nebulosas planetarias intercumulares y estructura del cúmulo

de Virgo. I4/2002A Marín (IAC), Sistemas de cúmulos globulares en galaxias elípticas. I2/2002A Martínez (IAC), Constrainig the Milky Way dark halo shape from the Sagittarius

tidal stream. I12/2002A Negueruela (Strasburg), Estrellas pre-sequencia-principal de masas intermedias

en cúmulos abiertos. I15/2002A Riera (Politécnica Cataluña), The fragmented wind-blown bubbles around

intermediate and massive stars. I7/2002A Vílchez (IAA), A search for Abundance Gradients in Ring Galaxies. I6/2002A

Jacobus Kapteyn Telescope

UK PATT

Boyce (Bristol), Hα imaging of gas-rich low surface brightness galaxies foundat 21cm. J/2002A/10

Burleigh (Leicester), Asteroseismology of a pulsating helium-atmospherewhite dwarf star. J/2002A/16

Davies (Edinburgh), Lightcurves of Near Earth Objects. J/2002A/8 Fitzsimmons (Belfast), Rapid-response astrometry of potentially hazardous

asteroids. J/2002A/12 Fitzsimmons (Belfast), The size and composition of Near-Earth Objects.

J/2002A/18 Green (Open University), Thermo-physical properties of a cometary NEO.

J/2002A/6 Hodgkin (IoA, Cambridge), Photometry of candidate halo white dwarfs. J/2002A/17 Jeffery (Armagh Observatory), Time-resolved observations of the pulsating

sdB star PG1605+072. J/2002A/7 Keenan (Belfast), Four-colour photometry of stars from the Palomar-Green

Survey. J/2002A/1 Marsh (Southampton), Cataclysmic Variable Stars from the 2dF QSO survey.

J/2002A/4 Marsh (Southampton), Companions to sub-dwarf binary stars. J/2002A/5 Morales-Rueda (Southampton), Measuring orbital periods of dwarf novae.

J/2002A/14 Norton (Open University), Multiwavelength Observations of SXTs: Black

Hole Accretion Disk Outbursts. J/2002A/2 Seigar (JAC, Hawaii), Optical properties of the disks of spiral galaxies. J/2002A/3 Tanvir (Hertfordshire), Rapid imaging of GRB error boxes and spectroscopy

of GRB-related optical/IR transients. J/2002A/13

NL NFRA PC

Röttgering (Leiden), A catalogue of galaxies near bright stars: preparing forVLT-AO and VLTI. j02an002

Salamanca (Amsterdam), Rapid imaging of GRB error boxes and spectroscopyof GRB-related optical/IR transients. w02an008 [sic]


4 2

SP CAT

Baes (Viena), Tracing the dynamic interplay between the gas-dominated andstar-dominated disk components in barred spirals. J1/2002A

Calabresi (Rome), Photometry of Centaur Object Chariklo. J2/2002A Casares (IAC), Optical reprocessing lines as tracers of companion stars in

LMXBs. JW19/2002A

Castro-Tirado (IAA-CSIC, LAEFF), La naturaleza de las explosionescosmicas de rayos gamma GRBs. JW11/2002A

Kidger (IAC), Definition of an accurate 1-30 micron flux calibration systemfor the GTC and SIRTF. J4/2002A, J4/2002B [sic]

López (Basel), ¿Hay barras lentas en galaxias interactuantes? J3/2002A Rosenberg (IAC), Calibración Homogénea de Cúmulos Globulares del Halo

Externo. J5/2002B [sic]

Telescope Time Awards Semester 2002B

For observing schedules please visit this web page:http://lpss33.ing.iac.es:8080/cgi-bin/schedules.pl

ITP Programmes on the ING Telescopes

Doressoundiram (Paris), Multi-color taxonomy of trans-Neptunianobjects. ITP/2002/1

Ruiz-Lapuente (Barcelona), Supernova and the physics of supernovaexplosions. ITP/2002/4

William Herschel Telescope

UK PATT

Blundell (Oxford), After the trigger: the time-resolved evolution of thehosts of powerful active galaxies. W/2002B/68

Crowther (University College, London), Properties of Wolf-Rayet stars inthe metal-rich environment of Andromeda (M31). W/2002B/60

Crowther (University College, London), Direct constraints on theexpansion velocity of hot, WN stars. W/2002B/61

Dalton (Oxford), Near Infrared Coverage of the Oxford INT DeepMulticolour Imaging Survey. W/2002B/32

Folha (Porto, Portugal), Excess Emission in T Tauri Stars: the Missinglink. W/2002B/54

Gray (Edinburgh University), Combined X-ray and weak lensing massprofiles of the brightest cluster lenses. W/2002B/74

Harries (Exeter), A search for Zeeman polarization in the emission linesof classical T Tauri stars. W/2002B/43

Jeffery (Armagh Observatory), Colorimetric mode identification inpulsating subdwarf B stars. W/2002B/27

Longmore (Royal Observatory, Edinburgh), Structure of and starformation limits in isolated dark globules. W/2002B/38

McLure (Edinburgh University), Black-hole mass measurement and thegeometry of the broad-line region in AGN. W/2002B/63

Meikle (Imperial College, London), Detailed study of the physics ofnearby Type Ia Supernovae. W/2002B/23 (Override, long term)

Meikle (Imperial College, London), Direct detection and study ofsupernovae in nuclear starbursts. W/2002B/56 (Long term)

Merrifield (Nottingham), 2000 Planetary Nebulae in M31: A DeepKinematic Survey. W/2002B/64

Naylor (Exeter), Is there structure in the substellar mass function?W/2002B/52

Nelemans (Cambridge), Testing common envelope theory and SN Iaprogenitor models with double white dwarfs. W/2002B/51

Page (MSSL-UCL), A pilot spectroscopic study of serendipitous hardspectrum XMM-Newton source. W/2002B/47

Pettini (Cambridge), CORALS II: Assessing the Dust Bias in DampedLyman α Systems at Intermediate Redshifts. W/2002A/10 (Long term)

Poggianti (Padova Observatory, Italy), Star formation and morphologicalevolution of galaxies in nearby clusters with WYFFOS. W/2002B/28(Long term)

Royer (Leuven, Belgium), A complete survey of the Wolf-Rayet content ofM33. W/2002B/16

Smail (Durham), Testing Photometric Redshifts using Cluster Lenses.W/2002B/7

Smith (Hertfordshire), Scattering geometries and the broad-line region inRadio-Quiet Quasars. W/2002B/20

Tanvir (Hertfordshire), Gamma-Ray Bursts: Origin, Physics and use asCosmological Probes. W/2002B/62 Override

Vink (Imperial College), A search for evidence of accretion in Herbig Bestars. W/2002B/4

Wilkinson (Cambridge), NGC2419 a radial velocity survey of anunusual stellar cluster. W/2002B/33

Willott (Oxford), The Fundamental Plane and black hole masses of z = 0.5radio galaxies. W/2002B/49

Wills (Sheffield), Triggering the Activity in Giant Elliptical Galaxies.W/2002B/9

NL NFRA PC

Förster Schreiber (Leiden), Near-infrared Snapshot Survey for BrightLensed Red High-redshift Galaxies. w02bn001

Ferguson (Groningen), A Search for Recent Massive Star Formation inGas-Rich Ellipticals /SOs. w02bn010

Hulleman (Utrecht), The nature of magnetars: UltraCam observations ofthe Anomalous X-Ray Pulsar 4U 0142+61. w02bn007

Jarvis (Leiden), An unbiased view of the gaseous environments of high-redshift radio galaxies. w02bn005

Kuijken (Groningen), M31 microlensing: checking Mira contaminationwith nIR AO imaging. w02bn011

Kuijken (Groningen), 2000 Planetary Nebulae in M31: a Deep KinematicSurvey. w02bn002

Mellema (Leiden), Polarization studies of the rings and haloes ofPlanetary Nebulae. w02bn008

OBrien (Amsterdam), Optical analogues of X-ray timing phenomena.w02bn003

Van den Heuvel (Amsterdam), The Origin and Physics of Gamma-RayBursts. w02bn004 Override

ES CAT

Barrado (LAEFF, Madrid), The Substellar Mass Function: Clues to theStar Formation Process. W7/2002B

Esteban (IAC, Tenerife), Abundancias químicas a partir de líneas derecombinación en nebulosas ionizadas. W3/2002B

Gallego (Complutense, Madrid), The evolution of the Star Formation Ratedensity of the Universe up to z = 0.8. W12/2002B

Gutiérrez (IAC, Tenerife), Búsqueda de galaxias de muy alto z a travésdel efecto lente gravitoria en cúmulos. W23/2002B

Gutiérrez (IAC, Tenerife), Fotometría en Hα y espectroscopía de objetoscon corrimientos al rojo anómalos. WN13/2002B

Martínez (Valencia), La masa y la extensión de los halos en galaxiaselípticas. W24/2002B

Mathieu (IAA, Granada), Do S0 galaxies follow the Tully-Fisher relation?W1/2002B

Negueruela (Alicante), La órbita de V0332+53. W9/2002B Paredes (Barcelona), Búsqueda de nuevos microcuásares: confirmación

espectroscópica de candidatos. W19/2002B Prieto (IAC, Tenerife), Estudio de galaxias con formación estelar extrema

a alto corrimiento al rojo. W27/2002B Shahbaz (IAC, Tenerife), High time resolution optical studies of quiescent

black hole X-ray transients. W25/2002B Zapatero (LAEFF, Madrid), Compañeros de objetos ultra fríos de la

vecindad solar. W16/2002B

IAC

Cepa (IAC, Tenerife), El proyecto OTELO: Cartografiado profundo en B yR de SA68 y NOAO-2h. W31/2002B

Rebolo (IAC, Tenerife), JOVIAN: detección directa de planetas gigantesalrededor de estrellas y aislados. IW32/2002B

TNG

Fasano (Padova), Star formation and morphological evolution of galaxiesin nearby clusters with WYFFOS. T022

Mannucci (Arcetri), A critical test of cosmological models: tracing theelusive filaments of hot intergalactic gas. T064

Moretti (Padova), Ages and metal abundances of star clusters in M33.T083


4 3

Saviane (ESO, Chile), Near-infrared luminosities of dwarf galaxies in theM81 group. T093

Isaac Newton Telescope

UK PATT

Baines (Leeds), Spectro-astrometry of Herbig Ae/Be and T Tauri stars.I/2002B/12

Fitzsimmons (Belfast), Rapid-response astrometry of potentiallyhazardous asteroids. I/2002B/18 (Override)

Gänsicke (Southampton), The cataclysmic variable population of theHamburg Quasar Survey. I/2002B/5

Irwin (Cambridge), A Panoramic CCD Survey of the Halo and Disk ofM31. I/2002B/24

Jameson (Leicester), Population II/III planetary nebulae and the propermotions of Pleiades BD candidates. I/2002B/8

Keenan (Belfast), A search for early-type stars in the haloes of distantgalaxies. I/2002B/1

Marsh (Southampton), Identification of faint stellar ROSAT sources.I/2002B/4

Maxted (Keele), Spectroscopy of detached eclipsing binaries in openclusters. I/2002B/23

McLure (Edinburgh University), A photometric redshift study of radiogalaxy environments. I/2002B/27

Meikle (Imperial College, London), Detailed study of the physics ofnearby Type Ia Supernovae. I/2002B/9 (Override, long term)

Tanvir (Hertfordshire), Gamma-Ray Bursts: Origin, Physics and use asCosmological Probes. I/2002B/28 (Override)

Williams (Queen Mary, London), The asteroidal population at theequilateral Lagrangian points of Saturn. I/2002B/2

NL NFRA PC

De Jong (Groningen), The MEGA Survey: Mapping Microlensing in M31.i02bn002

Ferguson (Groningen), A Panoramic CCD Survey of the Halo and Disk ofM33. i02bn006

Groot (Nijmegen), Beyond the Blue Edge in the Faint Sky VariabilitySurvey. i02bn004

Van den Heuvel (Amsterdam), The Origin and Physics of Gamma-RayBursts. w02bn004 (GRB override)

UK/NL WFS Programmes

van den Heuvel (Amsterdam), The Faint Sky Variability Survey II.WFS/2002A/1

McMahon (IoA), The INT Wide Angle Survey. WFS/2002A/8 Walton (ING), The Local Group Census. WFS/2002A/4 Watson (Leicester), An Imaging Programme for the XMM-Newton

Serendipitous X-ray Sky Survey. WFS/2002A/3

ES CAT

Aparicio (La Laguna), Large scale distribution of stellar populations inthe M33 halo. I13/2002B

Barrado (LAEFF, Madrid), Deep pencil-beam survey in a young, nearbycluster. I4/2002B

Carrero (IAC, Tenerife), Calibración del triplete del CaII como indicadorde metalicidad. I7/2002B

Fernández (IAA, Granada), Pérdida violenta de masa en estrellas jóvenesde tipo solar. I22/2002B

Garzón (IAC, Tenerife), Understanding of the structure of the Galaxy.I23/2002B

Herrero (IAC, Tenerife), Preparándose para OSIRIS: población estelarjoven de NGC 6946. I20/2002B

Herrero (IAC, Tenerife), Espectroscopía cuantitativa de estrellas Oionizantes. I5/2002B

Hidalgo (IAC, Tenerife), Estructuras a gran escala en galaxiasirregulares. I19/2002B

Montes (Complutense, Madrid), Spectroscopic and photometricmonitoring with high temporal resolution of flare stars. I1/2002B

Negueruela (Alicante), La distribución espectral de las estrellas Be.I6/2002B

Pohlen (IAC, Tenerife), The outer edge of the Galaxy. I11/2002B Ribas (Barcelona), Determinación directa de la distancia de M31 a partir

de binarias eclipsantes. I8/2002B Riera (Politécnica de Cataluña), The fragmented wind-blown bubbles

around intermediate and massive stars. I2/2002B

IAC

Balcells (IAC, Tenerife), Cartografiado profundo en U, V, e I paraCOSMOS y OTELO. I21/2002B

Rebolo (IAC, Tenerife), JOVIAN: detección directa de planetas gigantesalrededor de estrellas y aislados. IW32/2002B

Jacobus Kapteyn Telescope

UK PATT

Bucciarelli (Torino Observatory, Italy), Photometric Calibrators for thePalomar Sky Surveys. J/2002B/3

Burleigh (Leicester), Star Spots on Magnetic White Dwarfs. J/2002B/5 Fitzsimmons (Belfast), Rapid-response astrometry of potentially

hazardous asteroids. J/2002B/8 (Override) Keenan (Belfast), Four-colour photometry of stars from the Palomar-

Green Survey. J/2002B/2 (Long term) Littlefair (Exeter), Are young stars really spun down by their discs?

J/2002B/7 Marsh (Southampton), Companions to sub-dwarf binary stars. J/2002B/1 Maxted (Keele), Photometry of detached eclipsing binaries in open

clusters. J/2002B/10 McBride (Open University), Physical and thermal properties of Near

Earth Objects. J/2002B/6 Norton (Open University), Multiwavelength Observations of SXTs: Black

Hole Accretion Disk Outbursts. J/2002A/2 (Override, long term) Tanvir (Hertfordshire), Gamma-Ray Bursts: Origin, Physics and use as

Cosmological Probes. J/2002B/12 (Override)

NL NFRA PC

Röttgering (Leiden), A catalogue of galaxies near bright stars: preparingfor VLT-AO and VLTI. j02bn001

Tolstoy (Groningen), Photometric Zero Points in Local Group DwarfGalaxies. j02bn004

van den Berg (Brera Observatory, Italy), Photometry of peculiar X-raysources in the old open cluster NGC 6940. j02bn002

Van den Heuvel (Amsterdam), The Origin and Physics of Gamma-RayBursts. w02bn004 (GRB override)

ES CAT

Fuensalida (IAC, Tenerife), Medida del perfil vertical de turbulencia en elORM. J6/2002B

Kidger (IAC, Tenerife ), Fotometría de alta precisión de estrellasestándar para CanariCam. J7/2002B

Lara (IAA, Granada), Gas and dust analysis of the Jupiter family comets30P/Reinmuth 1 and 57P/duToit-Neujmin-Delporte. J1/2002B

López (IAC, Tenerife), Hay barras lentas en galaxias interactuantes?J2/2002B

Montes (Complutense, Madrid), Spectroscopic and photometricmonitoring with high temporal resolution of flare stars. JI1/2002B

Rodríguez (IAC, Tenerife), Estudio fotométrico de remanentes de novadébiles y poco estudiados. J3/2002B

IAC

Beckman (IAC, Tenerife), Stromgren photometry of stars from theHipparcos catalogue within 300 pc of the Sun. J8/2002B

Fuensalida (IAC, Tenerife), Medida del perfil vertical de turbulencia en elORM. J6/2002B

Kidger (IAC, Tenerife), Definition of an accurate 1 30 micron fluxcalibration system for the GTC and SIRTF. J4/2002B

Kidger (IAC, Tenerife), Fotometría de alta precisión de estrellas estándarpara CanariCam. J7/2002B

Rosenberg (IAC, Tenerife), Calibración homogénea de cúmulosglobulares del halo externo. J5/2002B

Abbreviations:

CAT Comité para la Asignación de TiempoES SpainIAC Instituto de Astrofísica de CanariasITP International Time ProgrammeNFRA Netherlands Foundation for Research in AstronomyNL The NetherlandsPATT Panel for the Allocation of Telescope TimePC Programme CommitteeSP SpainUK The United KingdomWFS Wide Field Survey

Contacts at ING Name Tel. (+34 922) E-mail (@ing.iac.es)ING Reception 425400Director René Rutten 425420 rgmrPersonal Secretary to Director Rachael Miles 425420 milesPublic Relations Javier Méndez 425464 jmaHead of Administration Les Edwins 425418 lieHead of Astronomy Danny Lennon 425441 djlHead of Engineering Gordon Talbot 425419 rgtTelescope Scheduling Ian Skillen 425439 wjiService Programme Saskia Prins 425463 stpWHT Manager Chris Benn 425432 crbINT Manager Romano Corradi 425461 rcorradiJKT Manager Romano Corradi 425461 rcorradiInstrumentation Technical Contact Tom Gregory 425444 tgregoryFreight Juan Martínez 425414 juan

ContentsMessage from the Director . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1The Isaac Newton Group of Telescopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2The ING Board and ING Directors Advisory Group . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2The ING Newsletter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

INGRID: EARLY SCIENCE RESULTS

J H KNAPEN, D L BLOCK, R BUTA, I PUERARI, B G ELMEGREEN, S STEDMAN, D M ELMEGREEN,Bar Strengths in Galaxies as Measured from INGRID Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

S MATTILA, R GREIMEL, P MEIKLE, N A WALTON, S RYDER, R D JOSEPH, Searching for Obscured Supernovae in Nearby Starburst Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

D GILBANK, I SMAIL, R IVISON, C PACKHAM, R BOWER, The INGRID MDS ERO Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9M BALCELLS, D CRISTÓBAL-HORNILLOS, M PRIETO, R GUZMÁN, J GALLEGO, A SERRANO, N CARDIEL, R PELLÓ,

The COSMOS NIR Survey with INGRID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

SCIENCE

J H J DE BRUIJNE, A P REYNOLDS, M A C PERRYMAN, A PEACOCK, F FAVATA, N RANDO, D MARTIN, P VERHOEVE, N CHRISTLIEB, Quasar Redshifts from S-CAM Observations: Direct Colour Determination of ~12 Gyr-Old Photons . . . . . . . . . . . . . . . . 14

R G SHARP, R G MCMAHON, S HODGKIN, C D MACKAY, The CIRSI-INT IR Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

TELESCOPES AND INSTRUMENTATION

R G M RUTTEN, The ING Telescopes in a Changing Landscape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19C R BENN, R ØSTENSEN, S ELS, F PRADA, T GREGORY, R MYERS, NAOMI Common-User Adaptive Optics at the WHT . . . . . . . 21J ACOSTA-PULIDO, E BALLESTEROS, M BARRETO, S CORREA, J M DELGADO, C DOMÍNGUEZ-TAGLE, E HERNÁNDEZ, R LÓPEZ, A MANCHADO,A MANESCAU, H MORENO, F PRADA, P REDONDO, V SÁNCHEZ, F TENEGI,

LIRIS: A Long-Slit Intermediate Resolution Infrared Spectrograph for the WHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22V DHILLON, T MARSCH, ULTRACAM TEAM, ULTRACAM Successfully Commissioned on the WHT . . . . . . . . . . . . . . . . . . . . . 25G TALBOT, M BLANKEN, R CORRADI, B GARCÍA, J PRAGT, A New Camera for WYFFOS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27C JACKMAN, Upgrading the WHT Acquisition TV Cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

OTHER NEWS FROM ING

R G M RUTTEN, A Workshop in Honour of Paul Murdin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Other ING Publications and Information Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29N SZYMANEK, J H KNAPEN, Real-Colour Images of Spiral Galaxies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29G TALBOTT, M BLANKEN, A CHOPPING, P JOLLEY, J REY, ING Stick to the TaskWork for the NSST . . . . . . . . . . . . . . . . . . . . . . 31R L M CORRADI,

A Euroconference Organised by the ING: Symbiotic Stars Probing Stellar Evolution, La Palma, 2731 May 2002 . . . . 32News from the Roque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34R L M CORRADI, Haloes of Planetary Nebulae from the INT WFC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Recent VIP Visits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Personnel Movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Seminars Given at ING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36The ING PR Collections of Images . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

TELESCOPE TIME

I SKILLEN, A New Definition of Dark, Grey and Bright Time at ING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Important Dates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Telescope Time Awards Semester 2002A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40Telescope Time Awards Semester 2002B . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

ISAAC NEWTON GROUP OF TELESCOPESRoque de Los Muchachos Observatory, La Palma

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