GMT Instruments and AO · 2008. 5. 28. · GMT Science Meeting - March 2008 9 GMACS – Overview • Multi-object, multi-slit spectrograph • 4x spectrographs, each with blue and

GMT Science Meeting - March 2008 1

GMT Instruments and AO


Instrument Status

• Scientific priorities have been defined• Emphasis on:

• Wide-field survey science (cosmology)• High resolution spectroscopy (abundances, Doppler planets)• Adaptive optics (planets, star formation, galaxy dynamics)

• Limited imaging capability• Queue-mode operating model adopted• Eight instrument concepts have been proposed• At different levels of development• Conceptual design studies are required• Down select will occur for ~ 3 first-light instruments


Instrument ConceptsInstrument Function λ range

(microns)Resolution FOV

GMACS

NIRMOS

Optical Multi-ObjectSpectrometer

0.35-1.0 250-4000 64-200arcmin^2

Near-IR Multi-ObjectSpectrometer

1.0-2.5 Up to ~4000 49arcmin^2

QSpec

SHARPS Optical High Resolution(Doppler) Spectrometer

0.4-0.7 150K 7 x 1” fibers

GMTNIRS

MIISE

HRCam

GMTIFS

Optical High ResolutionSpectrometer

0.3-1.05 30K1” slit

3” + fibre mode

Near-IR High-ResolutionSpectrometer

1.2- 5.0 25K-100K Single object

Mid-IR ImagingSpectrometer

3.0-25.0 1500 30”

Near-IR AO Imager 0.9-5.0 5-5000 30”

NIR AO-fed IFU 0.9-2.5 3000-5000 3”


Adaptive Optics Modes

Mode Description FOV Resolution Instruments

GLAO

LTAO

Ground LayerAdaptive Optics

7 arcmin 0.2 arcsec NIRMOS

Laser TomographyAdaptive Optics

30 arcsec 0.01 arcsec GMTIFS,HRCam

NGSAO

ExAO Extreme AdaptiveOptics

10 arcsec 0.01 arcsec HRCam

MCAO

MOAO

Natural Guide StarAdaptive Optics

10 arcsec 0.01 arcsec MIISE,HRCAM

Multi-ConjugateAdaptive Optics

90 arcsec 0.01 arcsec TBD

Multi-Object Adaptive Optics

10/90 arcsec 0.01 arcsec TBD


GMTNIRS

Instrument Capabilities

Wavelength (μm)1.0 10.00.3

Res

olvi

ng P

ower

5000

5000

050

0

5.0

HRCam

MIISE

GMTIFS

GMTNIRS

GMACSNIRMOS

QSpec

“Camera”


Accommodating Wide-Field and Narrow-Field/AO Instruments


Gregorian Instrument Mounting

• Large survey instruments mount below IP

• AO instruments - always “hot” – above IP


GMACS – Visible Multi-Object Spectrometer


GMACS – Overview

• Multi-object, multi-slit spectrograph• 4x spectrographs, each with blue and red arms• Field of view: 8 x 18 arcmin (~ 200 x 5 arcsec slits)• Wavelength range: 0.36 – 1.02 μm• Resolving power with 0.7 arcsec slit:

• R ~ 1400 in blue (215 km/s)• R ~ 2700 in red (110 km/s) (for accurate sky subtraction)• Cross-over at 6500 Å

• Collimated beam diameter: 300 mm• No direct imaging capability


GMACS – Optical Design x1


GMACS – Optical Layout x4


GMACS – Mechanical Layout

Mask changer4 x 2 channelField lens, slit mask, pick-off

mirrors

Disperser changer


NIRMOS – Near-Infrared Multi-Object Spectrometer


NIRMOS – Overview

• 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 λ coverage• 5 x 7 arcmin field of view• R ~ 3000 with 0.5 arcsec slits

• Augmented by GLAO


NIRMOS – Opto-Mechanical Layout


GMACS/NIRMOS InterchangabilityGMACS active NIRMOS active


Upper Instrument PlatformInstruments


Upper Instrument Platform10 m x 16.5 m


QSpec – Visible High Resolution Spectrometer


QSpec – Overview

• 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-pixel resolving power is R=125,000• Pupil anamorphism• White pupil design• VPH grating cross-dispersion• Four catadioptric cameras• 4k x 6.5k to 6k x 8k CCDs (with 15 µm pixels)


QSpec – Optical design

UV: 299 to 389 nm Blue: 383 to 545 nm

NIR: 723 to 1072 nmRed: 536 to 734 nm

1 m


QSpec on Instrument Platform


Gravity-Invariant QSpec on C-Ring


SHARPS – Super HARPS


SHARPS – Overview

• Planet Doppler spectroscopy• Fiber-fed: 7x (obj, sky, cal) x 1.0 arcsec fibers• Resolving power ~ 150,000• Wavelength: > 4400 – 6700 Å• White pupil spectrograph design• CCD mosaic detector• Deep depletion CCDs for red orders• Vacuum-enclosed spectrograph• High-stability thermal environment• Bulky enclosure


SHARPS – Optical Layout


SHARPS at Coudé Feed


GMTNIRS – GMT Near-Infrared Spectrometer


GMTNIRS – Overview

• Short Wavelength:• 1.2 – 2.4 μm (H & K covered in a single exposure)• Slit-limited resolving powers:

• R = 50,000, 0.3 arcsec slit ≡ 6 pixels• R3 immersion echelle grating• f/3 camera => 14 arcsec per order• 4096x4096 detector => 15 orders at K

• Long Wavelength (with AO):• 2 – 5 μm wavelength range• Diffraction-limited resolving powers:

• λ = 3.6 μm, R = 133,000, 0.06 arcsec slit ≡ 3 pixels• λ = 4.8 μm, R = 100,000, 0.08 arcsec slit ≡ 4 pixels

• f/7.8 camera => 0.85 arcsec per order at L• 2048x2048 detector


GMTNIRS – Optical Layout

200.00mmScale: 1/8Cold pupil

paraboloid

paraboloid from GMT

paraboloidprimary

tertiary

fpa

echelle

cross-disperser

200.00 mmScale: 1/8

slit

echelle

collimator

fold

primarysecondary

FPA

tertiary

crossdisperser

Short Wavelength Long Wavelength


GMTNIRS – Mechanical Layout


GMTNIRS on Instrument Platform


Adaptive Optics Instruments


Adaptive Optics Concept

• Single DM with common wave front sensing

• Asterism of 6 laser guide stars• Variable extent on sky

• Adaptive Secondary Mirror• Straight-through path to GLAO• Dichroic folds to LTAO,

thermal NGS, & ExAO• Diffraction limit:

• 0.010 arcsec at 1.0 μm• 0.020 arcsec at 2.0 μm• 0.040 arcsec at 4.0 μm• 3x better than Gemini


Scientific Impact of 0.016″ ImagesLTAO in the H band, 1 hr exposure, Antennae at z=1.4


Latest AO Reimaging Concept


AO System on Instrument Platform

LGSWFS


MIISE – Mid-Infrared Imaging Spectrometer


MIISE – Overview

• 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: 3-5 μm, 0.010 arcsec/pixel• Long wavelength channel: 8-25 μm, 0.030 arcsec/pixel


MIISE – Optical Design

input fromAO feed

3-5 micron detector

8-25 micron detector

2 micronphase sensorlong wavelength

imaging channel

nulling channel

dichroic


MIISE – Location at Direct Focus


GMTIFS – GMT Integral-Field Spectrograph


GMTIFS – Overview

• Single-object, AO-corrected, integral-field spectroscopy• Wavelength range: 1.0 – 2.5 μm• Resolving power: R = 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


GMTIFS – Optical Layout

Window TelescopeFocus

Imageplane

F-converter

Pupilplane

SlicerPupil Mirror Field Mirror

Collimator

FoldGrating Camera Detector


AO System on Instrument Platform

LGSWFS


HRCam – High Resolution Camera


HRCam – Overview

• Wavelength range: 1 – 2.5 μm• Sampling: 0.003 (f/46) and 0.010 (f/15) arcsec/pixel• Field of view: 13 (f/46) and 40 (f/15) arcsec• Detector: 4096x4096 pixels• Imaging:

• JHK + narrow bands• Sensitivity: Must reach H & K ~ 25 mag

• IFU spectroscopy: • 50x50 spaxels with 0.020 arcsec/spaxel• Resolving power: R ~ 3000 - 5000


HRCam – Optical Layout


Still to be developed…


Optical Reimaging Camera


Multiple Integral Field Spectroscopy

• ~ 10 IFUs• MOAO-fed• R ~ 4000• 0.1” spaxels


Summary

• Wide range of work-house capabilities• Will it address key science in 10 yr time?• Which will be the 1st generation instruments?• Are we catering for 2nd & 3rd generation instruments?


Documents

GMT Instruments and AO · 2008. 5. 28. · GMT Science Meeting - March 2008 9 GMACS – Overview • Multi-object, multi-slit spectrograph • 4x spectrographs, each with blue and