LGS AO at the W. M. Keck Observatory

Transcription

1 LGS AO at the W. M. Keck Observatory R. Campbell, D. Le Mignant, P. Wizinowich Photo Credit: Subaru Telescope 28 May 2005 UT 1

2 Acknowledge Co-Authors AO Scientists / Astronomers M. van Dam A. Bouchez J. Lyke A. Conrad R. Goodrich Engineering/Ops Team J. Chin E. Chock S. Doyle E. Johansson S. Kwok K. Grace C. Melcher R. Mouser D. Summers R. Sumner P. Stomski C. Wilburn 2

3 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operational Model The future of LGSAO at Keck 3

4 LGSAO Time Line 4

5 Keck II LGSAO Configuration Science Instruments NIRC2 OSIRIS NIRSPEC Enclosure with roof removed Elevation Ring Side Projection Laser Complicated Dye System 14 Watts Equivalent Rmag 9-10 ( ph sec-1 cm-2 AO Optics Bench Electronics Racks NIRC2 OSIRIS, Dual Star Module or NIRSPEC Nasmyth Platform Rails to deck 5

6 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operations The future of LGSAO at Keck 6

7 LGS AO Science LGS AO Refereed Science Papers (8 SOR, 1 Calar Alto, 2 Lick, 31 Keck II) Number of Papers Extra-galactic Galactic Solar System 8 By Instrument In 2007: 4 Year NIRC2, 11 OSIRIS, 3 7

8 Scientific Productivity, Keck AO IF LGS NGS LGS 8

9 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operations The future of LGSAO at Keck 9

10 NGSAO Image Quality Strehl vs. Magnitude NGSAO LGSAO FWHM 49mas LGSAO 10

11 Key Performance Areas Wave Front Controller 1 khz BW with laser 20x20 sub-apertures STRAP, R < 19mag Truth sensor (LBWFS) 20x20 Shack-Hartman Laser brightness ~9-10 Rmag Spot elongation, manageable problem Typical spot 2.0 x 2.2 arcsec Good UTT performance Regular Calibrations Once per run Daily afternoon check Side Projected Spot Elongation On Sky Optimization 11

12 Sky Coverage LGSAO 12

13 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operational Model The future of LGSAO at Keck 13

14 Observing Statistics Time Accounting of LGSAO Science at Keck 218 LGS Science nights 112 NIRC2 Open Shutter Science Time w/lgsao 27,4% 98 OSIRIS ( some dual instrument usage) 8 NIRSPEC Other Faults (inst+tel) 1,9% AO faults 7,3% Laser faults 5,4% Space Cmd Spotters Laser Traffic 0,5% Control 0,1% 0,9% Overheads (inst+tel+ao) 32,5% Weather 24,0% Weather Laser Traffic Control Spotters Space Cmd Laser faults AO faults Other Faults (inst+tel) Open Shutter Science Time w/lgsao Overheads (inst+tel+ao) 14

15 Weather Losses Removed, LGSAO Efficiency 36,1% Efficiency and Reliability 42,7% 2,4% 9,6% 7,1% 0,7% 0,1% 1,2% Priorities: Performance Reliability Laser Traffic Control Spotters Space Cmd Laser faults AO faults Other Faults (inst+tel) Open Shutter Science Time w/lgsao Overheads (inst+tel+ao) Efficiency : Opportunity for Improvement 15

16 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operation Model The future of LGSAO at Keck 16

17 LGSAO Night Operations 1 Observing Assistant / LGSAO operator 1 Laser Operator 5 Aircraft Safety Spotters 2 Support Astronomers 17

18 LGSAO Specific Preparations Detailed observing plans Targets/Instrument/Science priorities Dithering Schemes, Integration times, Calibrations Flexibility and interaction with Support personnel Location, Keck HQ or Mainland US. Pre-Observing meeting with Keck Support Astronomers Star List (targets) defined, submitted to Space Command 18

19 LGSAO Observing Specifics Instrument setup afternoon calibrations 4 O clock meeting LGS checkout (~30 min of dark time) Slew to TT star, propagate laser, close loops, offset to target Adjust program for SNR, weather, laser collisions, etc. Change instruments NGS / LGS Seeing limited instrument backup 19

20 Outline Background of LGSAO at Keck Scientific Productivity Performance Efficiency and Reliability Operational Model The Future of LGSAO at Keck 20

21 Keck I LGS AO Motivation Redundancy against failure of K2 LGS AO Improved performance relative to K2 LGS AO Greater flexibility in scheduling programs IF upgrade program assumes LGS AO on both telescopes Brighter LGS AO spot Laser: 20W (K1) vs. 14W (K2) Mode-locked CW has 2x coupling efficiency to Na Potential additional gains from improved Na coupling with narrower bandwidth & circular polarization Better performance from center projection (vs. side projection) Spot elongation reduced by 2x LGS aberrations symmetric & not a function of pupil angle Which instrument to move (OSIRIS?) Operation expected in

22 NGAO :Key new capabilities 1. Dramatically improved near-ir performance Significantly higher Strehls ( 80% at K) improved sensitivity Lower backgrounds improved sensitivity Improved PSF stability & knowledge improved photometry, astrometry & companion sensitivity 2. Increased sky coverage & Multiplexing Improved tip/tilt correction improved sky coverage Multiplexing dramatic efficiency improvements Much broader range of science programs 3. AO correction at red wavelengths Strehl of 15-25% at 750 nm highest angular resolution of any existing filled aperture telescope 4. Instrumentation to facilitate the range of science programs 22

23 Thank You More Info: Overview of Keck LGSAO, Wizinowich, P., et al. 2006, PASP, 118, 297. Performance of Keck LGSAO M.A. van Dam et al. 2006, PASP, 118, 310 LGSAO Operations Le Mignant et al., SPIE 2006 Proc.,