PALM-3000 and its back-end instruments are optimized for high-angular resolution science at visible and near-infrared wavelengths. As the world's highest order adaptive optics system, PALM-3000 corrects for atmospheric turbulence to an unprecedented degree using a new 3,388 actuator Xinetics deformable mirror in conjunction with the former 349 actuator Xinetics DM and separate fast tip-tilt mirror. Wavefront sensing requires a bright natural guide star in proximity to the science target.
2015A Call for Proposals
PALM-3000 will be available for PHARO science, shared-risk SWIFT science, and private instrument observations in 2015A.
The current performance of 160nm RMS has been demonstrated in 64x with V = 8 guide stars, which does approximately meet the design specification.
- PALM-3000 is operational and working through a period of 32x and 8x performance optimization. Wavefront correction in 64x has demonstrated performance in the range of 130-140 nm RMS wavefront error (equivalent to K-Strehl = 87%), which is nearing the ultimate expected performance level of 105 nm RMS (the 105 nm requirement is for a V = 5 guide star in median seeing conditions). The peak performance of PALM-3000 in excellent seeing (0.3" Ks) is 94% K-Strehl, corresponding to 85 nm RMS (July 2014).
- Instrument Status:
- PHARO (public)
- Is currently operational at the summit.
- SWIFT (public)
- Is performing routine science in both AO-fed and AO-passthrough (seeing-limited) operation.
- P1640 (private, PI: B. Oppenheimer, AMNH)
- Coronagraph + CAL is performing routine science in a large exoplanet imaging and spectroscopic survey.
- Fiber Nuller (private; PI: G. Serabyn, JPL)
- Initial FN tests with PALM-3000 successful in June 2012.
- TMAS (private; co-I's: R. Dekany and S. Hildebrandt, COO)
- First light successful 27 Sept 2012. Strategies for improving sensor quality are under investigation. Science observations in 2013B.
- DARKNESS (private; PI: B. Mazin, UCSB)
- Development of energy-resolving MKIDS technology imager funded by NSF in Summer 2013. First light schedule is TBD.
Measured Performance vs. NGS Brightness
- s64 pupil sampling mode: Small (8.3cm) subapertures
- We show below the P3K+PHARO K-band Strehl ratio obtained from September 2012 to July 2014 taken in median or better seeing conditions (1.2 or better Ks seeing) over more than 12 nights total. The mean bright star (brighter than 8th mv) Ks strehl ratio obtained in median or better seeing conditions NEAR ZENITH and after low order non common path errors are removed is 86%. When moving off of zenith, if the non common path errors are not removed, strehl ratios will degrade by 10-40% depending on local conditions. Contact the Palomar staff for more information.
- s32 pupil sampling mode: Larger (16.2 cm) subapertures
- We have successfully commissioned the 32x pupil sampling mode during our engineering night on March 22, 2013. The Palomar staff can now operate P3K in the 32x pupil sampling mode.
- Based on expected P3K performance and our experience on targets between March and August 2013 (see figure below), we suggest using 64x mode on targets brighter than 10 mv if the visible seeing is at or better than 1.0". For target stars fainter than 9 mv in visible seeing greater than 1.0", 32x mode may perform better than 64x. The Palomar staff can help you determine which mode may be best given the local conditions.
- 32x did out-perform 64x on 11.5 and 13 mv target stars on the night of March 22, 2013 in 15-20 mph surface winds and variable seeing conditions (1.0-1.7 Ksh seeing).
- s8 pupil sampling mode: Largest (65 cm) subapertures
- We have successfully commissioned the 8x pupil sampling mode during our engineering night on July 8, 2014. The Palomar staff can now operate P3K in 64x, 32x, and 8x pupil sampling modes.
- 8x mode is under-performing by ~ 50% on targets fainter that 11 mv in median seeing. We are working on 8x performance upgrades in early FY15.
- Performance and acquisition optimizations are on-going through FY15.
Expected System Capabilities
For 2015A, PALM-3000 will support natural guide star wavefront sensing (only) in the following correction modes:
PALM-3000 correction will be best in the direction of the guide star, and fall off due to atmospheric anisoplanatism. The corrected field of view diameter will vary with conditions, but is generally expected to be between 1-2 arcmin diameter in K-band, decreasing to 10-20 arcsec in I-band.
| Number of subapertures per pupil diameter || WFS limiting mag || WFS best performance mag || Notes |
| 64 || V < 11 || V < 7 || |
| 32 || V < 13 || V < 10 || |
| 8 || V < 17 || --- || |
Guide Star Selection
PALM-3000 has a patrol range for NGS selection of ~90 arcsecond in diameter (allowing a guide star up to 90" away from the science target to be utilized, with the understanding that anisoplanatism error (not accounted for in any data elsewhere on this page) degrades performance significantly beyond ~30 arc sec radius in H/K bands (and beyond ~15 arc sec in Y/J bands.)
The WFS acquisition camera FOV is ~ 95 arc sec x 80 arc sec (TBC).
Ultimate Expected Performance on Bright Guide Stars
The bright star wavefront error budget for PALM-3000 is as follows:
- Mean turbulence weighted wind speed = 9.5 m/s
- Zenith pointing
- Guide star brightness V ~ 5
- AO mode: s64
| Seeing || r_0(0.5um) || RMS residual wavefront error || Strehl Ratio || Notes |
| || || || r' || i' || Z || Y || J || H || K || |
| || || || 0.62um || 0.75um || .88um || 1.03um || 1.25um || 1.64um || 2.2um |
| 0.7" || 0.14 m || 83 nm || 48% || 61% || 70% || 78% || 84% || 90% || 95% || Variations in non-common-path errors may limit PHARO K Strehl to ~90% even in excellent seeing |
| 1.1" (median) || 0.092 m || 105 nm || 32% || 46% || 57% || 66% || 76% || 85% || 91% || See above |
| 1.6" || 0.07 m || 165 nm || 26% || 38% || 47% || 54% || 61% || 68% || 73% || - |
Expected Observing Overheads
Instrument requirement #0480 states that PALM-3000 shall be ready to begin a science exposure < 2 minutes after the end of a telescope slew (< 1 minute goal). During science observing in 2015A, we expect observations performed in a single AO mode in a localized part of the sky to approach 2 minutes. Large changes in telescope pointing or AO pupil mode will add 5 minutes to the acquisition overhead.
Closed-loop AO image dithering on PHARO is expected to be functional at a level equal to or better than the prior PALMAO system (smallest step size ~ 5 mas), with improved non-common-path flexure during long exposures. Early engineering tests confirm PALM-3000 has improved flexure stability compared to PALMAO. These results are being quantified.
We do not recommend precision wide-field PHARO astrometric programs, due to the uncharacterized nature of our dual-DM-conjugate correction architecture. Contact the PALM-3000 PI for further details.
PALM-3000 is designed to support NGS observations of Uranus and Neptune, but optimization on these targets will require additional calibration effort. To date, in S64 mode, good correction has been obtained locking on Saturn's moon Titan (V~8 and diameter ~ 1"). Contact the PALM-3000 PI for further information.
Technical inquiries for specific observing proposals not addressed here can be referred to Principal Investigator Richard Dekany at Caltech Optical Observatories or Rick Burruss at JPL (email@example.com 818.354.2155).