Instrument Concepts
Instrument
Function
l range
Resolution
FOV
(microns)
GMACS
Optical Multi-Object
Spectrometer
0.35-1.0
250-4000
36-144
arcmin^2
NIRMOS
Near-IR Multi-Object
Spectrometer
1.0-2.5
Up to ~4000
49
arcmin^2
QSpec
Optical High Resolution
Spectrometer
0.3-1.05
30K
1” slit
3” + fibre mode
SHARPS
(G-CLEF)
Optical High Resolution
(Doppler) Spectrometer
0.4-0.7
150K
7 x 1” fibers
GMTNIRS
Near-IR High-Resolution
Spectrometer
1.2- 5.0
25K-100K
Single object
MIISE
Mid-IR Imaging
Spectrometer
3.0-25.0
1500
30”
HRCam
Near-IR AO Imager
0.9-5.0
5-5000
30”
GMTIFS
NIR AO-fed IFU
0.9-2.5
3000-5000
3”
Science with Giant Telescopes - Jun 15-18, 2008
1
History
GMT instrument conceptual design studies – 2005
Internal to GMT consortium (at that time)
GMT conceptual design review – February 2006
Subsequent work by project, with partner participation:
Integration of seeing-limited instruments
Reconfiguration of instrument platform
AO relay
Meetings:
Seeing-limited instruments workshop
Adaptive optics workshop
Planet RV workshop
Science with GMT (Canberra) – March 2008
Before proceeding, need to resolve instrument-AO interface
Science with Giant Telescopes - Jun 15-18, 2008
2
GMT Instrument Design Studies
• Request letters of intent
(e.g. Sep 2008)
• Select list for design studies (~ 6?)
(Nov 2008)
• Request for proposals released
for each instrument
(Jan 2009)
• Proposals due
(Mar 2009)
• Award contracts for design studies
(May 2009)
• Negotiate study contracts,
contract start
• Finish design studies and review
(Jul 2009)
(Dec 2010)
• Select first light instruments,
start instrument development
Science with Giant Telescopes - Jun 15-18, 2008
(2011)
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Some Issues
Intention of design studies is to form actual instrument teams
– across (and beyond) partner institutions
Design study funding:
project $
in-kind
(probably not telescope time – too sensitive)
Evaluation:
Internal – hard to avoid some conflicts
External
Science with Giant Telescopes - Jun 15-18, 2008
4
Science with Giant Telescopes - Jun 15-18, 2008
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GMACS
• Multi-object, multi-slit spectrograph
• 4x spectrographs, each with
red and blue arms, VPH gratings
• Field of view: 8 x 18 arcmin
• Wavelength range 0.36 – 1.02 μm
• Collimated beam diameter: 300 mm
Science with Giant Telescopes - Jun 15-18, 2008
• Resolving power w/ 0.7 arcsec slit:
R ~ 1400 in blue
R ~ 2700 in red
(for accurate sky subtraction)
cross-over at 6500 Å
• Separate 8 x 9 arcmin imaging
channel
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GMACS – Optical Layout x4
Science with Giant Telescopes - Jun 15-18, 2008
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NIRMOS
• Wavelength range: 0.85 – 2.5 μm
• Imaging Mode:
• 7 x 7 arcmin field of view
• 0.067 arcsec/pixel
• 6kx6k detector
• Spectroscopy Mode:
• Multi-slits: 140 x 3 arcsec long,
full wavelength coverage
• 5 x 7 arcmin field of view
• R ~ 3000 with 0.5 arcsec slits
• Augmented by GLAO
Science with Giant Telescopes - Jun 15-18, 2008
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GMACS, NIRMOS & MIISE
Science with Giant Telescopes - Jun 15-18, 2008
9
QSpec
• Four beam instrument
• 450 mm beam diameter
• R4 echelle gratings (x2):
200 x 1600 mm
• Rφ = 30,000 arcsecs
• λλ = 300 nm to 1.07 µm
(in four channels)
• 2-pix resolution: R=125,000
• Pupil anamorphism
• White pupil design
• VPH grating cross-dispersion
• Four catadioptric cameras
• 4k x 6.5k to 6k x 8k CCDs
(15 µm pixels)
Science with Giant Telescopes - Jun 15-18, 2008
Red: 536 to 734
nm
NIR: 723 to 1072
nm
1m
UV: 299 to 389
nm
Blue: 383 to
545 nm
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SHARPS
• Planet Doppler spectroscopy
• Fiber-fed: 7x(obj,sky,cal) x 1.0” 
• Resolving power ~ 150,000
• Wavelength: > 4400 – 6700 Å
• White pupil spectrograph design
Science with Giant Telescopes - Jun 15-18, 2008
• CCD mosaic detector
• Deep depletion CCDs for red orders
• Vacuum-enclosed spectrograph
• High-stability thermal environment
• Bulky enclosure
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MIISE – Mid-IR Imaging Spectrometer
3-5 μm detector
8-25 μm
detector
input from
AO feed dichroic
nulling channel
long wavelength
imaging channel
2 micron
phase sensor
Science with Giant Telescopes - Jun 15-18, 2008
• Wavelength range: 3 - 25 μm
• Field of view: 30 – 40 arcsec
• Resolving power: R ~ 1500
• Modes:
• Imaging
• Spectroscopy
• Nulling (8-25 μm)
• Coronography (3-5 μm)
• Short wavelength channel: 3-5μ,
0.010 arcsec/pixel
• Long wavelength channel: 8-25μ,
0.030 arcsec/pixel
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GMTIFS – GMT Integral Field Spectrograph
•
•
•
•
Single-object, AO-corrected, integral-field spectroscopy
Wavelength range: 1.0 – 2.5 μm
Resolving power: 4000 – 5000
Range of spatial sampling and fields of view:
• Galaxy dynamics: 0.05-0.10 arcsec sampling, 2-3 arcsec FOV
• Black hole masses: Diffraction-limited sampling, small FOV
Spaxel size along slit (arcsec)
0.008
0.016
0.032
0.054
Slitlet width (arcsec)
0.020
0.040
0.080
0.135
Field of view (arcsec)
0.80
1.6
3.2
5.4
Tel focus
F-converter
slicer
fold
collimator
detector
grating
Science with Giant Telescopes - Jun 15-18, 2008
camera
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