SPIE, San Diego, CA - 1 August 2005 Bruno Altieri, XMM-Newton European Space Astronomy Centre Page 1 The XMM-Newton Slew Survey: processing challenges

SPIE, San Diego, CA - 1 August 2005SPIE, San Diego, CA - 1 August 2005Bruno Altieri, XMM-Bruno Altieri, XMM-NewtonNewton

European Space Astronomy CentreEuropean Space Astronomy CentrePage Page 11

The XMM-The XMM-NewtonNewton Slew Survey: Slew Survey: processing challengesprocessing challenges

Richard SaxtonRichard Saxton11,,Bruno AltieriBruno Altieri11, Diego Bermejo, Diego Bermejo44, , M. Pilar EsquejM. Pilar Esquej1,41,4, Michael Freyberg, Michael Freyberg33, Veronica , Veronica LazaroLazaro44, Andy Read, Andy Read22

11 ESAC, ESA, Spain ESAC, ESA, Spain22 University of Leicester, U.K. University of Leicester, U.K.33 MPE, Garching, Germany MPE, Garching, Germany44 Universidad Complutense de Madrid, Spain Universidad Complutense de Madrid, Spain



Talk outlineTalk outline

Survey characteristicsSurvey characteristics ProcessingProcessing Attitude reconstruction: Astrometry Attitude reconstruction: Astrometry (1)(1) Spurious sourcesSpurious sources

• Optical loading Optical loading (2)(2)• Detector flashes Detector flashes (3)(3)

SensitivitySensitivity Extended sourcesExtended sources



XMM-XMM-NewtonNewton 3 mirror modules 3 mirror modules

with 58 shells with 58 shells eacheach

EPIC:EPIC:• 2 MOS CCD 2 MOS CCD

camerascameras• 1 pn CCD 1 pn CCD

cameracamera

2 Reflecting 2 Reflecting Grating Grating SpectrometersSpectrometers

1 Optical Monitor1 Optical Monitor

Mirrors

RGS-Camera 1 RGS-Camera 2

EPIC-MOS-Camera 2 EPIC-MOS-Camera 1

EPIC-pn-Camera Optical Monitor

RGS



Survey Survey CharacteristicsCharacteristics

Average slew length : 86 degrees



OverviewOverview- 465 slew datasets in archive (since Rev 314, end-2001)- 465 slew datasets in archive (since Rev 314, end-2001)- PN, MOS-1/2 exposures in Medium filter with the observing mode set - PN, MOS-1/2 exposures in Medium filter with the observing mode set

to that of previous pointed observationto that of previous pointed observation- Data initially available for slews longer than 30 minutes duration- Data initially available for slews longer than 30 minutes duration- Open-slew speed = 90 degrees / hour, i.e. on-source time ~14 secs- Open-slew speed = 90 degrees / hour, i.e. on-source time ~14 secs- Area covered to date ~8000 deg- Area covered to date ~8000 deg2 2 (~20% of sky)(~20% of sky)

ecliptic coordinates

great circles passing through ecliptic poles due to sun constraint.



Processing strategyProcessing strategy

• Tangential projection not valid over whole slew. Divide slew into 1 deg2 images and recalculate sky positions.

• Source search using near-standard pipeline eboxdetect/emldetect combination tuned for ~zero background.

• Use sources with DET_ML > 10 equivalent to 3.9 sigma

• Search independently in three bands and produce three catalogues :

soft (0.2-2 keV) hard (2-12 keV) total (0.2-12 keV)

Dedicated pipeline MPE/ESAC/LUX with database at ESAC



Initial impressionsInitial impressions

Source extended into a 4 arcmin streak due to 2.6 second frame time

Full frame (73ms) mode streak = 6 arcsecs – not noticeable

Extra pn sensitivity + additional MOS background means little to be gained from analysing MOS slews

Epic-pn attitude reconstruction good

MOS PN PN (eFF)

Extended full frame streak of 18 arcsecs

Slew direction

We can process slew data with a small s/w change (available in SAS 6.5)

New operations strategy (from end of 2004):New operations strategy (from end of 2004):

MOS slews will be used for calibrationMOS slews will be used for calibration All PN slews longer than 15 mins will be down-linked and All PN slews longer than 15 mins will be down-linked and

processed and used for scienceprocessed and used for science Medium filter if FF,EFF,LW and Closed for other modesMedium filter if FF,EFF,LW and Closed for other modes



EPIC-pn source characteristicsEPIC-pn source characteristicsSource Count Distribution Exposure Time Distribution

Minimum @ 4 counts Maximum @ ~ 10 secondsMean 6.3

- Can calculate flux limits for the XMM slew survey



Current StatusCurrent Status (15/07/2005)

20052005 20102010 20152015

Equivalent Equivalent fraction of fraction of sky coveredsky covered

20 %20 %

(25)*(25)* 50%50%

(60)(60)80%80%

(100)(100)

Number of Number of sourcessources

40004000

(5000)(5000)1000010000

(12000)(12000)1600016000

(20000)(20000)

Completeness

* Including high background slews

• Initial processing of 374 slews (297 are FF, eFF or LW) – 25% have high background

• Images created and source searched for 138 slews giving

1596 sources in total band1596 sources in total band1231 sources in soft (0.2-2.0 keV) 1231 sources in soft (0.2-2.0 keV) bandband221 sources in hard (2.0-12.0 221 sources in hard (2.0-12.0 keV) bandkeV) band

At faint end, 169 soft-band andAt faint end, 169 soft-band and61 hard-band sources, not 61 hard-band sources, not detected in the total banddetected in the total band

Source density: Source density: ~0.5 sources ~0.5 sources per square degreeper square degree

• 60% have RASS counterpart



Astrometry: initial comparisonAstrometry: initial comparison

Comparison with ROSAT survey positions shows a wide distribution, with a tail up to 1 arcmin

median=31” offset



Attitude Problem: correctionAttitude Problem: correction

Two types of positional error

(1) Real error of ~10″

(2) Error of 0-60″ (mean 30″) but only in slew direction

Slew direction

AB Dor

‘Error ellipse’ around source (slew-oriented)

Good relative astrometry: ~10 arcsec, but poor absolute astrometry: ~30 arcsec

Systematic shift was evidenced, traced to :• quantisation of time to 1 second in AHF • timing error in the RAF, due to a delay of 0.75s of the star tracker CCDs leading to a systematic offset



Achieved astrometric accuracyAchieved astrometric accuracy

RASS : 16” Simbad : 8”

Close to the theroretical limit !



Optical Loading – A Problem?Optical Loading – A Problem?

Contrary to pointed observations, no offset maps is computed/applicable.

Possibility of optical loading contamination



UY VirUY VirDSS Image 2’×2’ Total band (0.2-12 keV)

Hard band (2-12 keV)Soft band (0.2-2 keV) (RASS src)



Optical Loading – A Problem?Optical Loading – A Problem?

CD 36-1289 : X-ray emission from this V=10.5 star, but none from neighbours at V=6.5 and V=7.6

Several examples like this

- No correlation between source counts and Vmag for bright stars- Consistent with optical loading predictions: 5 counts expected above 200eV only for stars brighter than V=3.75

No optical loading problems : genuine X-ray sources

R Magnitude (USNO)

0.2

-2.0

keV

counts



Detector problemsDetector problems

Affects one CCD so are detector related

Often appear as non-single events

Very soft spectrum with a peak at 100 eV Events occur mostly within 1 frame

Detector map shows eventsConfined to 1 CCD.



Detector flashesDetector flashes

Short duration CCD flashes with very soft spectrum

Effect minimized by using single events only below 500 eV



Starting the NASSStarting the NASS(Newton All-Sky Survey (Newton All-Sky Survey

Aitoff projection galactic coordinates



RASS:RASS: 5.0x10-13 (92% of sky)

EMSS:EMSS: 3.0x10-12 (2% 0f sky)

HEAO-1:HEAO-1: 3.6x10-11 (all-sky)

Exosat:Exosat: 5.0x10-11 (?% of sky)

RXTE:RXTE: 1.0x10-11 (all-sky), but with only 1° positional accuracy

X-ray All-Sky Surveys : Flux limitsX-ray All-Sky Surveys : Flux limits

NASS:NASS:6(4.5) 10-13 ergs s-1 cm-2 in the soft band (0.5-2.0 keV)4(3) 10-12 ergs s-1 cm-2 in the hard band (2-10 keV)



Extended source analysisExtended source analysisSource 2: 2x2 arcmin

FF mode point sources are fitted well by a PSF, e.g. source 4

Low background and tight PSF gives good sensitivityTo extended sources

Enough counts to detect extension in brightest sources



Example extended sourcesExample extended sources

Easily detected as extended in 14 second exposure

Abell 3581 2 SNRs in SMC



XMM-Slew

Galaxy ClustersGalaxy Clusters



Four GalaxiesFour Galaxies

ESO443-IG005Mrk 352

MCG 04-53-021 NGC5899

Non-RASS



Sources detected in separate slewsSources detected in separate slews

- Source detected in 3 separate slews: Rev 0570, Rev 0573, Rev 0574

- Known ROSAT source (+faint galaxy)

- Evidence for variability (factor ~2)



Two Merging Two Merging Galaxy PairsGalaxy Pairs

NGC 4748

II Zw 742



Correlations with ROSATCorrelations with ROSAT

XMM soft

RO

SA

T

Mean XMM/ROSAT ~ 10



Correlations with ROSATCorrelations with ROSATAll Slew sources:Hardness ratio vs Galactic latitude

Blue circles:No RASS counterpart

Red crosses:RASS counterpart

Hard sources not seen by ROSAT

RASS sources on average softer than non-RASS sources



Extremely Bright SourcesExtremely Bright Sources

Several LMXB at few hundred c/s



Conclusions from current Slew analysisConclusions from current Slew analysis

138 slews source-searched (using best strategies): 1596 sources found in 3400 deg² (~10% of sky) ~0.5 sources per square degree

Soft X-ray band detection limit close to ROSAT BS catalogue Hard X-ray band detection limit deepest ever:

> 10× deeper than EXOSAT, HEAO-1 ~ 2.5× deeper than RXTE (only has 1° positional accuracy)

Good sensitivity to extended sources, investigating optimum detection techniques

XMM-Slew positional accuracy ~8″

Aim to recover science from high-background slews

Encountering & solving problems en route …

Aim to issue first slew source catalogue before end of 2005



Well Known SourcesWell Known Sources

N132D







Spurious Sources…Spurious Sources…

… due to crab off-axis !Sources 1 & 3 of Pilot#1



ScheduleSchedule- Initial processing of slew data- Initial processing of slew data (finished)(finished)- Solve attitude/astrometry problems – - Solve attitude/astrometry problems – asapasap- Creation of images, source searching, rejection of spurious sources- Creation of images, source searching, rejection of spurious sources (Feb to July)(Feb to July)- - Investigate optimum extended source extraction methodsInvestigate optimum extended source extraction methods (April to Oct)(April to Oct)- Creation of final catalogue for ingestion into XSA- Creation of final catalogue for ingestion into XSA (Aug to Oct) (Aug to Oct)- Ingestion into XSA- Ingestion into XSA (end of November) (end of November)- - Provide flux / upper limits serverProvide flux / upper limits server (early 2006) (early 2006)

- Search co-added slews Search co-added slews (?)(?)- Investigate going down to DET_ML=8 Investigate going down to DET_ML=8 (?)(?)

- - Regular updates with newly processed slewsRegular updates with newly processed slews

Documents

SPIE, San Diego, CA - 1 August 2005 Bruno Altieri, XMM-Newton European Space Astronomy Centre Page 1 The XMM-Newton Slew Survey: processing challenges