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Keck LGS AOPlanning Workshop:

Overview, Requirements & Schedule

December 5, 2004

The LGS AO Team

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DMScienceCamera

STRAP

LBWFS

TTM

WFS

NGS

WavefrontController

Focus

Centroids

Tip/tilt

IR transmissivedichroic

LGS

Sodium transmissive

dichroic

Lenslets

Offload to telescope

Offload focus to

telescope

(Tip/tilt to Laser)

Light fromTelescope

LGS AO Control

Pupil Orientation(Subaperture gains)

TSS x,y,z stage

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Dye Laser

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Laser Table (on EL ring)

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Proposed Top Level Requirements

1. Sky Coverage2. Strehl Ratio3. PSF stability & knowledge4. Observing Capabilities (nodding,

science fov, etc)5. Observing Efficiency 6. Reliability & uptime7. Cost (to operate & maintain)8. Schedule (timeliness)

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1. Sky Coverage

1Bahcall & Soneira, 1981; 2Keck Report 208, 1996.

Sky Coverage vs. NGS Limiting Magnitude(Varying Galactic Lat. and Field of View)

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9

10

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14

15

16

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0.10% 1.00% 10.00% 100.00%

Sky Coverage

Re

fere

nc

e S

tar

Ma

gn

itu

de

(R

-ba

nd

)

30'' FOV @ 45º lat

60'' FOV @ 45º lat

60'' FOV @ 0º lat

1Bahcall & Soneira, 1981; 2Keck Report 208, 1996.

NGS

LGS

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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

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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

• 2nd LGS milestone requirement has a high priority on demonstrating– SR = 0.2 for V 15 & SR = 0.1 for V 17

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Error Budget# Error Term RMS Error (nm) What LGS errors can be reduced?

NGS LGS1 Camera 113 113 Fixed by NIRC2. Different for OSIRIS or NIRSPEC.2 Fitting 128 128 Fixed by DM.3 Telescope 60 60 Fixed by telescope + AO.4 Bandwidth - TT 128 128 Depends on STRAP optimization.

5 Bandwidth - DM 80 80Improve with optimizing subaperture gains (from LBWFS) & better system matrix.

6 Measurement 80 100Balance with DM bandwidth error. Improve with laser beam quality, optimal focus on Na layer & more power.

7 Measurement -elongation 0 112 Fixed by projector location8 Measurement - laser jitter 0 50 Implement slow or fast up-link tip/tilt.9 Measurement - TT 0 40 Depends on NGS magnitude. Trade off vs TT bandwidth10 Other NGS 105 105 Fixed11 Focal Anisoplanatism 0 155 Fixed by atmosphere (d0=4.5m from 10-night Oct&Dec/02 campaign).12 LGS Calibrations 0 150 Reduce by using LBWFS centroid offsets.13 Telescope focus 0 30 LBWFS to FCS control (0.17 mm error = 0.016" blur)14 Other LGS 0 70 ?

RSS = 270 381

Strehl at 2.1 um = 0.52 0.27 Our 1st light LGS milestone requirement was SR = 0.2

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First LGS Results (UT 9/20)

Extraordinary seeing

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LGS Image on Acquisition Camera

30 sec ACAM Image250 counts at 500 HzBest spot 1.1x1.7”11/17/03 9:49 HST

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3. PSF Stability & Knowledge

• No requirement currently defined– Laser power & image size stability may be important

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4. Observing Capabilities• Science Instruments

– NIRC2, NIRSPEC, OSIRIS (July/04 1st 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

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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.

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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).

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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 1st 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.

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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 2nd 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

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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

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8. Schedule: LGS AO Top-level Milestones

• Top-level milestones (as of fall/02): 9/03 - 1st corrected images on NIRC2 with laser

• Achieved Sept. 18 & 19, 2003

– 12/03 – LGS AO facility operable by AO experts– 3/04 – 1st engineering science– 6/04 – 1st shared risk science– 3/05 – Operable for science by OA & 1 expert– 6/05 – 1st queue scheduled science?

• How important is timeliness?– ESO & Gemini should have lasers in 2004

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Current EmphasisLGS facility operable by AO experts (12/03) & 1st 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.

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Current Emphasis - Task Flow Down # Subsystem Priority Task Lead Team Planned Actual Status (12/4/03)

1 STRAP 1,2 Significantly reduce background AB PW 11/05/03 11/24/03 Significantly reduced. Filter wheel remains2 STRAP 1,2 Replace filter wheel homing source JC 01/05/04 Approach identified3 STRAP 1,2 Optimize to achieve 5(?) mas rms on V=17 EJ MvD Closed on 16.4 & briefly on 17.1.4 STRAP 1,2 How do you eval STRAP perf on V>13? MvD 12/18/03 Evaluating data5 STRAP 1,2 Fix diaphragm JC EJ 10/21/03 10/21/036 STRAP 1,2 Operational use of diaphragm EJ AB 12/18/03 Need calibrated positioning.7 STRAP 1,2 Determine if Na rejection needed EJ PW,AB 11/24/03 11/24/03 Need for 17 mag star. Installed on 11/24.8 STRAP 1,2 Implement background compensation offset EJ MvD 12/18/03 Tried unsuccessfully on 11/17.9 STRAP 3,6,9 Hardware integration into WFC JC EJ 01/22/04 4 open slots made in WFC crate10 STRAP 3,6,9 Software integration into WFC EJ 01/15/04 #1 priority after 11/17 run. Plan for 12/9.11 STRAP Decision on spares for STRAP PLW 12/31/0312 LBWFS 1,2 Significantly reduce background AB PW 11/05/03 11/24/0313 LBWFS 3 Define next steps in auto & calib & proceed DLM SH,MvD 11/07/03 New subaperture wting being implemented14 LBWFS 3 Automate LBWFS calibration EJ DLM,SH Turn off clipping.15 LBWFS 6 Autoset integration time vs STRAP signal PS SH,EJ 11/26/03 Need to revise test plan16 LBWFS 7,8 Realign &/or eliminate vignetting over 20x20" PW AB 11/25/03 11/18/03 Measured vignetting. 17 LBWFS 7,8 Maintain lenslet-DM registration over 20x20" DLM EJ 01/30/04 Follows realignment18 LBWFS Maximize unvignetted field & center it PW AFM beamsplitter is major vignetting source19 LBWFS 1,2 Determine wavefront measurement accuracy AB EJ,PW 12/15/0320 LBWFS 1,2 Review/update measurement requirement AB EJ,PW 12/15/0321 LBWFS 3 Review/approve LBWFS manager doc PS AB,EJ 12/02/0322 LBWFS 1,2 Optimize optical quality PW AB 12/01/03 12/01/03 Realigned lenslets & CCD & CCD focus23 LBWFS 1,2 Measure/understand background EJ SH 12/04/03 Prelim dark current measurement made24 TSS 6,7,8,9 Auto reposn up to 20" off-axis in < 10 sec PS 10/07/0325 WFS focus 1,2,5 Increase FCS range to >~250 mm PW 10/07/03 More needed? 265 mm is possible (255 now)26 WFS focus 1,2,6 Autozero LBWFS focus by adjusting Na alt DS 10/11/0327 Laser pting 1,2,6,9 Offload average WFS t/t to laser pointing AB DS 12/10/03 Infra works. Need summation. M3 hysteresis fixed.28 Laser pting 1,2 Determine how soon UTT needed MvD AB 11/20/03 Power spectrum tool on-line29 Laser pting 6,7 M3 EPICS control from OBS JC SH 10/30/03 11/17/03 Demoed on 11/17.30 Laser pting 6 Autoposn M3 vs elevation RL DS 12/10/03 Model done. Some data acquired on 11/17.31 Laser pting 6,7 Autoposn M3 up to 20" off-axis in <10 sec DS 12/18/03 11/17 test. Dir & scale factor meas at 1 rot angle. 32 Laser pting 8,9 Autoposn laser pting for a 5x5" nod DS 12/18/03 11/17 test. Dir & scale factor meas at 1 rot angle. 33 Laser 1,2 Document reln between PIB & pting AB DS,RL 01/10/04 Doc prepared. Needs to update with more images.34 Laser 1,2 Document reln between on-sky & PIB image AB JC 01/10/04 Needs more work, esp ACAM images35 Laser 1,2 Automate taking of ACAM images of LGS AB 12/15/03

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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).

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K2 AO Observing Schedule (12/03-7/04)Dec Jan Feb Mar Apr May Jun Jul

1 NIRC2 1 LGS LGS IF 1 IF IF/2 2 2 LGS LGS IF 2 IFsci IF3 3 3 NIRC2 IF/ NIRC2 3 IFsci IF4 4 4 NIRC2 IF IFsci 4 NIRC2 IF5 NIRC2 IF/NIRC2 NIRC2 IF IFsci 5 NIRC2 NIRC26 NIRC2 IF NIRC2 6 6 /LGS /NIRC2 NIRC27 NIRC2 IF 7 7 7 LGS /NIRC2 NIRC28 NIRC2 IF 8 8 8 8 8 NIRC29 LGS/NIRSP NIRC2 9 9 9 9 LGS NIRC2

10 NIRSP NIRC2 10 NIRC2 10 10 LGS NIRC211 NIRSP NIRC2 11 11 11 11 10 /NIRC212 NIRSP NIRC2 12 12 12 12 11 NIRC213 NIRSP 13 13 13 13 13 12 /NIRC214 NIRC2 14 14 14 14 14 13 1415 LGS 15 15 15 15 15 14 1516 LGS 16 16 16 16 16 15 1617 LGS 17 17 17 17 17 16 1718 18 18 18 18 18 18 17 1819 19 19 19 19 19 19 18 1920 20 20 20 20 20 20 19 2021 21 21 21 21 21 21 NIRC2 2122 22 22 22 22 22 22 NIRC2 2223 NIRC2 23 23 23 23 NIRSP/NIRC2 NIRC2 2324 NIRC2 24 24 24 24 NIRSP/NIRC2 NIRC2 OSIRIS25 NIRC2 25 25 25 25 NIRSP NIRC2 OSIRIS26 NIRC2 26 26 26 NIRC2 NIRSP NIRC2 LGS27 27 27 27 27 NIRC2 NIRSP NIRC2/ 2728 28 28 NIRC2 28 28 NIRC2 28 2829 NIRC2 29 LGS 29 29 NIRC2 29 /LGS30 NIRC2 30 30 30 IF/ 30 3031 NIRC2 31 IF/ IF 31

39%of nightsuse AO