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GSMT

Progress on the 30m Giant Segmented Mirror Telescope AURA New Initiatives Office Leiden, 17 May 2001 Matt Mountain Jim Oschmann Knut Olsen. GSMT. Partnership between Gemini, NOAO and our communities Science Enabled Implementation Concepts Resources Interfaces Issues.

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GSMT

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  1. Progress on the 30m Giant Segmented Mirror TelescopeAURA New Initiatives OfficeLeiden, 17 May 2001Matt MountainJim OschmannKnut Olsen

  2. GSMT • Partnership between Gemini, NOAO and our communities • Science Enabled • Implementation Concepts • Resources • Interfaces • Issues

  3. Science & Instrument workshops • Madison MAXAT science - 1998 • Woods Hole MAXAT technology -1999 • Tucson MAXAT instruments -2000 • Tucson GSMT science – 2000 • Subsystem working group meetings 1999-2000 • Systems, optics, structures… • OPTICON, Edinburgh, Leiden

  4. GSMT System Considerations- Astronomers View Science Mission - DRM’s Adaptive Optics Active Optics (aO) Full System Analysis Support & Fabrication Issues Instruments GSMT Concept (Phase A) Site Characteristics Enclosure protection

  5. Derived Top Level Requirements

  6. 30mGiant Segmented Mirror Telescope concept GEMINI 30m F/1 primary, 2m adaptive secondary

  7. The Enemies….. • Wind….. • The Atmosphere……

  8. Enabling techniques • Active and Adaptive Optics • Active Optics already integrated into Keck, VLT and Gemini • Adaptive Optics “added” to Keck, Gemini (and soon) VLT • Active and Adaptive Optics will have to be integrated into GSMT Telescope and Instrument concepts from the start

  9. GSMT Control Concept LGSs provide full sky coverage Deformable M2 : First stage MCAO, wide field seeing improvement and M1 shape control • M2: rather slow, large stroke DM to compensate ground layer and telescope figure, • or to use as single DM at >3 m. (~8000 actuators) • Dedicated, small field (1-2’) MCAO system (~4-6DMs). Active M1 (0.1 ~ 1Hz) 619 segments on 91 rafts 10-20’ field at 0.2-0.3” seeing 1-2’ field fed to the MCAO module Focal plane

  10. AO Technology constraints (50m telescope) r0(550 nm) = 10cm No. of Computer CCD pixel Actuator pitch S(550nm) S(1.65mm) actuators power rate/sensor (Gflops) (M pixel/s) 10cm 74% 97% 200,000 9 x 105 800 25cm 25% 86% 30,000 2 x 104 125 50cm 2% 61% 8,000 1,500 31SOR (achieved) 789 ~ 2 4 x 4.5 Early 21st Century technology will keep AO confined to l > 1.0 mm for telescopes with D ~ 30m – 50m

  11. MCAO on a 30m: summary • MCAO on 30m telescopes should be used l > 1.25 mm • Field of View should be < 3.0 arcminutes, • Assumes the telescope residual errors ~ 100 nm rms • Assumes instrument residual errors ~ 70 nm rms • Equivalent Strehl from focal plane to detector/slit/IFU > 0.8 @ 1 micron • Instruments must have: • very high optical quality • very low internal flexure Rigaut & Ellerbroek (2000) l(mm) Delivered Strehl 1.25 0.2 ~ 0.4 1.65 0.4 ~ 0.6 2.20 0.6 ~ 0.8 9 Sodium laser constellation 4 tip/tilt stars (1 x 17, 3 x 20 Rmag)PSF variations < 1% across FOV

  12. AO an integral part of the GSMT Concept • Low order correction for wind buffeting and “seeing improvement” • 3 Natural Guide stars give full sky coverage • Narrow Field AO requires at least one LGS for l<5mm • Science requires low emissivity implementation • MCAO requires multiple NGS and multiple DM’s

  13. R = 10,000 R = 1,000 R = 5 Comparative performance of a 30m GSMT with a 6.5m NGST Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration GSMT advantage NGST advantage

  14. R = 10,000 R = 1,000 R = 5 Comparative performance of a 30m GSMT with a 6.5m NGST 100 m Assuming a detected S/N of 10 for NGST on a point source, with 4x1000s integration R = 5 OWL advantage NGST advantage e = 15%

  15. GSMT Implementation concept- wide field (1 of 2) Barden et al (2001)

  16. Optical “seeing improvement” using low order AO correction Image profiles are Lorenzian 16 consecutive nights of adaptive optics the CFHT

  17. GSMT Implementation concept- wide field (2 of 2) • 20 arc minute MOS • on a 30m GSMT • 800 0.75” fibers • R=1,000 350nm – 650nm • R=5,000 • 470nm – 530nm • Detects 13% - 23% • photons hitting 30m • primary 1m Barden et al (2001)

  18. GSMT Implementation concept- MCAO/AO foci and instruments Oschmann et al (2001) MCAO opticsmoves with telescope elevation axis MCAO Imager at vertical Nasmyth 4m Narrow field AO or narrow field seeing limited port

  19. Spot diagrams for MCAO + Imager Diffraction limited performance for 1.2mm – 2.2 mm can be achieved

  20. MCAO Optimized Spectrometer • Baseline design stems from current GIRMOS d-IFU tech study occurring at ATC and AAO • ~2 arcmin deployment field • 1 - 2.5 µm coverage using 6 detectors • IFUs • 12 IFUs total ~1.5”x1.5” field • ~0.05” spatial sampling R ~ 6000 (spectroscopic OH suppression)

  21. GSMT Implementation concept- MCAO/AO foci and instruments Oschmann et al (2001) MCAO opticsmoves with telescope elevation axis MCAO Imager at vertical Nasmyth 4m Narrow field AO or narrow field seeing limited port

  22. GSMT Implementation concept- MCAO/AO foci and instruments Oschmann et al (2001) MCAO opticsmoves with telescope elevation axis MCAO Imager at vertical Nasmyth 4m Narrow field AO or narrow field seeing limited port

  23. High resolution, high Signal/Noise observations Detecting the molecular gas from gaps swept out by a Jupiter mass protoplanet, 1 AU from a 1 MO young star in Orion (500pc) (Carr & Najita 1998) GSMT observation ~ 40 mins (30 mas beam)

  24. GSMT will need an Adaptive Secondary 30cm actuator pitch Good conditions (0.5" seeing): lambda diameter["] %energy 1.25000 0.0226732 0.338447 1.60000 0.0290217 0.473207 2.25000 0.0408118 0.613434 3.8 0.71 5.00000 0.0906928 0.758112 10.0000 0.181386 0.789314 20.0000 0.362771 0.797315 50cm actuator pitch Good conditions (0.5" seeing): lambda diameter["] %energy 1.25000 0.0226732 0.251838 1.60000 0.0290217 0.395080 2.25000 0.0408118 0.559923 3.8 0.66 5.00000 0.0906928 0.744220 10.0000 0.181386 0.785671 20.0000 0.362771 0.796393 8,960 actuators, 30cm spacing on Primary 3,225 actuators, 50cm spacing

  25. Sky coverage andStrehl for narrow field, thermal infrared observations using an adaptive secondary(wind buffeting on M1)(Rigaut, 2001) • for l < 10mm single laser beacon required

  26. End-to-End Approach • Science Requirements (including instruments) • Error Budget • Enclosure concept • Interaction with site, telescope and budget • Telescope structure • Interaction with wind, optics and instruments • Optics • Interaction with telescope, aO/AO systems and instruments • AO/MCAO • Interaction with telescope, optics, and instruments • Instruments • Interaction with AO and Observing Model • Observing Model

  27. Wind Loading • Driving characteristic may be wind • Lower wind sites with good seeing • How to protect telescope • Enclosure needs • May be more limiting than local seeing to performance • Cost drivers • Advance methods for correcting More critical than for existing telescopes

  28. Average pressure PSD DATA- effect of enclosure shutters

  29. average pressure PSD by EL • Note: No elevation dependence on average pressure on primary

  30. How to scale to 30 meters:Average pressure SF (C00030oo) RMS pressure differences D(d) = 0.096 d 0.41 30M Spatial scale

  31. An enclosure is essential: scaled up and taller variation of JCMT Enclosure

  32. 30mGiant Segmented Mirror Telescope concept Horizon Pointing - Mode 1 = 2.16 Hz

  33. Response to Wind Current concept will now go through “second iteration” of design In response to wind analysis

  34. Point DesignInitial Analysis • Finite element model of structure • Gravity sag and initial modal analysis • Wind PSD’s calculated from Gemini tests • To be applied to current model • Structure function approach to scaling Gemini data on wind buffeting to 30 meter • Preparing to apply wind buffeting to point design • Aid in systems flow down of requirements • Early trades possible soon

  35. Objectives: Next 2 years • Develop point design for GSMT & instruments • Carried out within NIO • Attack key technical problems • Adaptive optics • Wind loading • Mirror segment fabrication • Continue community involvement in defining: • Science & technical requirements • Instrumentation options; technology paths • Support design studies that complement other projects (CELT, FELT, OWL, etc.)

  36. Resources: Next 2 years • Combined Gemini partnership + NOAO resources: $2.1M • Core NIO effort focused on studies to: • Analyze point design • Attack key technical issues • Develop instrument and subsystem concepts • Explore science and instrument requirements • Additional US National efforts: $2.0M external studies: • Enable community efforts: science; instruments • Study contracts • Broad community workshops • Enable key external engineering studies; alternate concepts • End-to-end system model + detailed error budget • Alternate system design concept studies • Alternate AO system design and modeling studies • Develop site testing equipment; apply in Chile

  37. AURA New Initiatives Office Adaptive Optics Francois Rigaut (Gemini)

  38. GSMT STEERING COMMITTEE Present Members John Casani Jet Propulsion Laboratory Alan Dressler Carnegie Observatory Richard Ellis CalTech Bob Fugate Starfire Optical Range Jay Gallager University of Wisconsin Bob Gehrz University of Minnesota Riccardo Giovanelli Cornell University Bob Kirshner Harvard-Smithsonian, CfA Rolf Kudritzki University of Hawaii Simon Lilly HIA Joe Miller University of California Jerry Nelson University of California Larry Ramsey Penn State University Chuck Steidel CalTech 

  39. Interfaces • Community task groups; workshops • NSF, other Gemini Agencies (PPARC, NRC, ARC..) • Potential partners: CELT; ESO; others • Other next generation telescope projects • Private sector/government lab consultants • NIO steering committee • US System steering group • GSMT is the apex of US system • System must support GSMT • OPTICON

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