1. 1 Keck LGS AO Planning Workshop: Overview, Requirements & Schedule December 5, 2004

2. The LGS AO Team

3. 3 DM Science Camera STRAP LBWFS TTM WFS NGS Wavefront Controller Focus Centroids Tip/tilt IR transmissive dichroic LGS Sodium transmissive dichroic Lenslets Offload to telescope Offload focus to telescope (Tip/tilt to Laser) Light from Telescope LGS AO Control Pupil Orientation (Subaperture gains) TSS x,y,z stage

4. 4

5. 5 STRAP & LBWFS Opto- mechanics

6. 6 Dye Laser

7. 7 Laser Table (on EL ring)

8. 8 Proposed Top Level Requirements 1.Sky Coverage 2.Strehl Ratio 3.PSF stability & knowledge 4.Observing Capabilities (nodding, science fov, etc) 5.Observing Efficiency 6.Reliability & uptime 7.Cost (to operate & maintain) 8.Schedule (timeliness)

9. 9 1. Sky Coverage 1 Bahcall & Soneira, 1981; 2 Keck Report 208, 1996. NGS LGS

10. 10 1. Sky Coverage 80% at 45° GL requires NGS R=19 & 60” tip/tilt fov STRAP/LBWFS magnitude limit: –Demonstrated V=16.4 with STRAP –Demonstrated V=15 with LBWFS –At V=17.1 found Na background to be ~ equal to NGS flux. Have installed sodium rejection filter. –At V=17.1 found bench background ~ ½ of NGS flux. Subsequently reduced one source. Still need to deal with STRAP filter wheel source. STRAP/LBWFS field of view: –Current fov > 30x30” (somewhat off- centered). –Off-axis vignetting by acquisition fold beamsplitter to be addressed

11. 11 2. Strehl Ratio Strehl requirement at K’ –SR  0.25 for V  16 –SR  0.1 for V  19 Status: –In NGS mode achieve SR = 0.52 at K’ for V = 9 –Demonstrated SR = 0.36 at K’ for V = 14 NGS w/ excellent seeing –Achievable Strehl ratio defined by error budget –MK seeing campaign (Oct&Dec/02; 10-nights) measured d0= 4-5m. –Subsequent work on reducing background, optimizing STRAP & realigning LBWFS should help performance 2 nd LGS milestone requirement has a high priority on demonstrating –SR = 0.2 for V  15 & SR = 0.1 for V  17

12. 12 Error Budget

13. 13 First LGS Results (UT 9/20) Extraordinary seeing

14. 14 LGS Image on Acquisition Camera 30 sec ACAM Image 250 counts at 500 Hz Best spot 1.1x1.7” 11/17/03 9:49 HST

15. 15 2. Strehl Ratio: Tasks to achieve STRAP: –Optimization –Background reduction LBWFS: –Optimization of centroiding –Focus offloading to FCS –Image sharpening to WFS –Pixel binning –Background reduction WFS: –Subaperture gains vs pupil orientation Laser: –Improved image quality –Higher output power –Circularly polarized –Slow &/or fast up-link tip/tilt

16. 16 3. PSF Stability & Knowledge No requirement currently defined –Laser power & image size stability may be important

17. 17 4. Observing Capabilities Science Instruments –NIRC2, NIRSPEC, OSIRIS (July/04 1 st light) Science Object & LGS Positioning –Independent positioning over 40x40” NIRC2 field of view. –Able to position science object to NGS-level accuracy. –Able to position LGS to  0.5” Elevation range –Able to observe from 30°  EL  85°. Nodding –Two modes: LGS fixed or moves with science object. –Maximum individual nod  10” Rotator –Vertical or position angle mode

18. 18 5. Observing Efficiency Corrected images on science camera after slew  2 min longer than the LBWFS exposure time  5 min for a V=19 NGS The NGS autosetting tool requires ~ 1 min after slew Nod time  20 sec (including opening & closing loops) Requires STRAP integration into WFC for automation Laser overhead  30 min/night Currently achieving this Additional potential time losses. Shuttering of laser due to: Cirrus/clouds. Laser traffic control collisions. 1-4 times per night. Aircraft. Very rare. Satellites. Space command has provided no blackouts.

19. 19 6. Reliability, Uptime & Operability Reliability & Uptime –  10% of nighttime lost to problems Achieved 2.5% with K2AO for 5 Interferometer runs between April & Oct. (143 clear hrs) –Average uninterrupted observing time > 3 hrs Achieve this now for NGS All software tested & released in a controlled version. Successful completion of an operational readiness review (ORR).

20. 20 7. Operational Costs Maintenance –Requirement:  2 days of laser maintenance / month  1 day of LGS AO maintenance / month –$50k/yr in parts (primarily for laser) Run setup & calibrations –Requirement:  1 day of AO expert & 1 day of laser expert / run  2 hrs of AO expert & 2 hrs of laser expert / night –Currently: Laser: 1 day prior to run + ~ 5 hrs on 1 st day of run + ~ 3 hrs on subsequent days. 2-3 people. AO: ~ 5 hrs on day of run + ~ 2 hrs on subsequent days. ~ 5 people.

21. 21 7. Operational Costs Nighttime Operation –Requirement:  1 AO/laser expert in addition to regular crew. –Currently entire team for engineering nights. Laser at Summit: Chin & Lafon all night, Lynn for start-up + 4 spotters LGS AO at HQ: Bouchez, Hartman, Johansson, Le Mignant, Stomski, Summers, van Dam, Wizinowich –For 2 nd milestone reduce to 3 AO + 1 laser expert + spotters –Plan to test remote laser nighttime operation in Dec. All monitoring from summit control room during Nov. night Currently small tweaks needed at least at start of run (but getting better) –Need to implement at least wide field camera(s) to get FAA approval for no spotters. May also require mosaic radar. Cost Summary (assuming 10 runs & 70 nights/yr) – Maintenance + setup + nighttime = 3d/m*12m + (2d/r*10 + 0.5d/n*70n) + 1.5d/n*70 = 196d = 0.9 FTEs –Labor + parts  $150k/yr

22. 22 Requirements Summary Potential Criteria Performance Success Criteria: 1.Achieve a Strehl  0.25 in Kp for a V  16 mag NGS. 2.Achieve a Strehl  0.1 in Kp for a V  19 mag NGS. 3.Corrected images on science camera  5 min after slew. 4.Nod time  20 sec (including opening & closing loops). Operability Success Criteria: 5.LGS AO operation over 30°  EL  85°. 6.  40x40” field of view to science camera. 7.  60” diameter field for tip/tilt & LBWFS NGS. 8.Nodding demonstrated over a  5x5” field. 9.Vertical and positional angle modes. 10.  10% of nighttime lost to problems. 11.Average uninterrupted science time > 3 hrs. 12.All software tested & released in a controlled version. 13.Successful completion of an operational readiness review (ORR). 14.Operational costs  $150k/yr. LGS AO operable by OA +  1 expert

23. 23 8. Schedule: LGS AO Top-level Milestones Top-level milestones (as of fall/02): 9/03 - 1 st corrected images on NIRC2 with laser Achieved Sept. 18 & 19, 2003 –12/03 – LGS AO facility operable by AO experts –3/04 – 1 st engineering science –6/04 – 1 st shared risk science –3/05 – Operable for science by OA & 1 expert –6/05 – 1 st queue scheduled science? How important is timeliness? –ESO & Gemini should have lasers in 2004

24. 24 Current Emphasis LGS facility operable by AO experts (12/03) & 1 st eng. science (3/04). Performance Success Criteria: 1.Achieve a Strehl > 0.2 in Kp for a V > 15 mag NGS. 2.Achieve a Strehl > 0.1 in Kp for a V > 17 mag NGS. 6.Corrected images on science camera < 5 min after slew. 9.Nod time < 20 sec (including opening & closing loops). Operability Success Criteria: 3.LGS AO operable by 3 AO + 1 laser expert (+ NIRC2 operator). 4.All software tested & released in a controlled version (by Dec. 15) 5.Demonstrate correction over 50° < EL < 85°. 7.Off-axis science demonstrated for a target > 20 arcsec from NGS. 8.Nodding demonstrated over a 5x5” field. Numbers indicate relative priorities. Faint performance higher priority than off-axis operation Performance documentation included in above tasks.

25. 25 Current Emphasis - Task Flow Down

26. 26 Science Demonstration Engineering science demonstration (see DLM presentation) Includes system characterization for science Shared risk science LGS AO availability for shared risk science with NIRC2 in 04B (starts Aug/04) requires Observatory notification by ~ Feb. 3. Will have had Dec. eng. nights + Feb. 1&2. Need to document performance for this shared risk availability. Available for shared risk science with OSIRIS in 05A? Science operations Operational Readiness Review by early Aug. for 05A (or early Feb. for 05B). Initially with NIRC2 only. Handover to Operations Group Handover Review (after 1 or 2 semesters of science).

27. 27 K2 AO Observing Schedule (12/03-7/04) 39% of nights use AO