TAURUS Tunable Filter and astronomical applications

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TAURUS Tunable Filter and astronomical
applications

• Sonia Cianci
• (USyd / AAO)

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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

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TAURUS operating modes

• Tunable imaging - TTF
• 3D line mapping
• Multi-slit spectroscopy
• Polarimetry

• All operating modes support
• Time series observations
• charge shuffling
• nod and shuffle

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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

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FPs as tunable filters
m ? 2 ? l cos ?
R m N
dR dm dl
---- ---- ---
R m l
4 - 40
100 - 1000
1.5 - 15 ?m
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TTF resolving power
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Periodic TTF transmission profile
7.0 ?m
12.0 ?m
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TTF order sorting filters
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TTF blocking filters designed to fit within
windows free of OH night-sky emission
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Orion (H?, NII6583, SII6717)
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MR 2251-178 the Largest Known Quasar Nebula
(Shopbell, Veilleux, Bland-Hawthorn 1999)

• One of the few radio-quiet quasars with an
  extended gaseous nebula
• Spiral complex extends more or less symmetrically
  over 200 kpc
• M(nebula) lt 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

H?
jet axis
maximum vel. gradient
Z 0.0638
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
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D.H. Jones thesis
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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).

• 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, age500Myr, mass0.06M?
• 3 x 2.5 hour chunks which showed significant
  evidence for variability.

2Kx4KCCD
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Instrument illuminates centre of 15?m
pixel 2Kx4K CCD
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Can also image in closely spaced emission /
absorption lines...
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TTF charge shuffle imaging
NGC2437 (planetary nebula)
Ratio maps are possible in non-photometric
conditions...
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NGC 2437 (H?, NII, SII)
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Straddle shuffling
Bland-Hawthorn Jones, 1998
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Star formation in bright ellipticals Galaxy is
source of noise, not signal Straddle shuffling
draws out faint emission
Ferguson et al. 2001
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Nod and shuffle KGB JBH 2001
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Standard Spectrscopy with interpolation

• 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!

Nod and shuffle with simple subtraction
KGB JBH 2001
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M82
H? N II HST
Warm ionised gas from superwinds is sometimes
seen out to 10 - 15 kpc from the galaxy nucleus
(Shopbell Bland-Hawthorn 1998 Devine Bally
1999 Shopbell et al. 2001)
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Concluding 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

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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/