TAURUS Tunable Filter and TAURUS Tunable Filter and astronomical applicationsastronomical applications

Sonia CianciSonia Cianci

(USyd / AAO)(USyd / AAO)

Overview:Overview:

• TAURUS Tunable Filter– What it is, and how it works– Observing modes

• time series imaging• frequency switching• straddle shuffling• nod and shuffle

– Astronomical applications

TAURUS operating modesTAURUS operating modes

• Tunable imaging - TTFTunable imaging - TTF

• 3D line mapping

• Multi-slit spectroscopy

• Polarimetry

All operating All operating modes support:modes support:

- Time series Time series observationsobservations

- charge shufflingcharge shuffling

- nod and shufflenod and shuffle

TTF: What is it?TTF: What is it?

• Pair of Fabry-Perot interferometers– Blue arm: 3700 - 6500 Å– Red arm: 6500 - 9600 Å– Bandpass: 6 - 60 Å– 10 arcmin field at f/8 on AAT (0.37’’ per pixel)

• Each arm has two highly polished glass plates

• High performance coatings

• Piezoelectric stacks to control plate separation

FPs as tunable filtersFPs as tunable filters

m = 2 l cos

R = m N

dR dm dl

R m l---- = ---- = ---

100 - 1000 4 - 40 1.5 - 15 m

TTF resolving powerTTF resolving power

7.0 7.0 m

12.0 12.0 m

Periodic TTF transmission profilePeriodic TTF transmission profile

TTF order sorting filtersTTF order sorting filters

TTF blocking filters designed to fit within windows free of OH night-sky emission

Orion (H, [NII]6583, [SII]6717)

MR 2251-178: the Largest Known Quasar NebulaMR 2251-178: the Largest Known Quasar Nebula

• One of the few radio-quiet quasars with an extended gaseous nebula

• Spiral complex extends more or less symmetrically over ~ 200 kpc

• M(nebula) < 6 x 1010 Msun (ionized)

• Photoionized by the quasar

• Smooth large-scale rotation, in opposite sense to the inner region of the galaxy

• Morphology and large-scale rotation seem to rule out origin from cooling flow, past merger event, or interaction with nearby galaxy G1

• Favor a model in which the extended ionized nebula resides within a large complex of HI gas centered on the quasar

(Shopbell, Veilleux, & Bland-Hawthorn 1999)

H

Z = 0.0638

maximum vel. gradient

jet axis

Sensitivity: ~ few 10-18 erg s-1 cm-2 arcsec-2 (m ~ 1 cm-6 pc ~ 0.5 R) – 10x fainter than typical narrow-band images…

D.H. Jones

thesis

Time Series Tunable Filter • TTF can be used in a time

series mode, where charge shuffling is used to acquire a series of interleaved bands with very small dead time (~1s).

2Kx4KCCD Slot Mask

9’ TaurusField

B1

B2

B1

B1

B2

B1

B2

B1

B2

• February & August 1998 observed in trying AAT conditions (ie. rain, cloud & 4” seeing), but got several 2.5 hour sequences on LP 944-20

• M9.5 type brown dwarf, age=500Myr, mass=0.06M

• 3 x 2.5 hour chunks which showed significant evidence for variability.

Instrument illuminates centre of 15m pixel2Kx4K CCD

TTF takes data in first bandpass

Charge is shuffled into “storage” area

TTF switches to second band and takes a second image

TTF switches back to the first band and collects more photons

Charge is shuffled back down

And then the charge shuffles again, and collects more photons in the second band

And so on …..And so on ….. And so on …..

Can also image in closely spaced emission / absorption lines...

TTF charge shuffle imaging

Ratio maps are possible in non-photometric conditions...

NGC2437 (planetary nebula)NGC2437 (planetary nebula)

NGC 2437 (H, [NII], [SII])

Straddle shufflingStraddle shuffling

Bland-Bland-HawthornHawthorn & Jones, 1998 & Jones, 1998

Star formation in Star formation in bright ellipticals:bright ellipticals:

Galaxy is source of Galaxy is source of noise, not signalnoise, not signal

Straddle shuffling Straddle shuffling draws out faint draws out faint emissionemission

Ferguson et al. 2001Ferguson et al. 2001

`Nod and shuffle’

KGB & JBH 2001

• Observations of brown dwarf D1228

• 1800s with nodding along slit every 30s.

“Standard” technique is limited by the crappy slit, flat fielding, etc.

“Nod & Shuffle” produces Poisson noise!

“Standard” Spectrscopywith interpolation

Nod and shufflewith simple subtraction

KGB & JBH 2001KGB & JBH 2001

M82 M82

(Shopbell & Bland-Hawthorn 1998; Devine & Bally 1999; Shopbell et al. 2001)

H + [N II] HST

11 kpc500 pc

Warm ionised gas from Warm ionised gas from superwinds is sometimes superwinds is sometimes seen out to ~ 10 - 15 kpc seen out to ~ 10 - 15 kpc from the galaxy nucleusfrom the galaxy nucleus

Concluding remarksConcluding remarks• TTF is a very versatile instrument

• Different observing modes allow for wide variety of applications, e.g.:

• faint emission• time variability• resolution of closely spaced emission/absorption lines• differential imaging (even in bad conditions!), etc.

• Future tunable instruments being developed by AAO:– OSIRIS - for GranTeCan 10m– DAZLE - for VLT 8m

References:

Bland-Hawthorn, J. (2000) ASP Conference Series, 195, 34

Bland-Hawthorn, J. & Jones, D.H. (1998) SPIE, 3355, 855

Devine, D. & Bally, J. (1999) ApJ, 510, 197

Ferguson, A., van der Hulst, T. & van Gorkom, J. (2001) AAO Newsletter, No. 96 (February)

Glazebrook, K. & Bland-Hawthorn, J. (2001) PASP, 113, 197

Shopbell, P.L. & Bland-Hawthorn, J. (1998) ApJ, 493, 129

Shopbell, P.L., Veilleux, S. & Bland-Hawthorn, J. (1999) ApJ, 524, L83

TTF Web page: http://www.aao.gov.au/ttf/