* A note on the P3K WFS upgrade: P3K underwent a significant upgrade to the WFS camera and RTC system during the 2019B semester, culminating in a successful re-commissioning of the 64x mode in November 2019. This mode has been in regular use since, and has demonstrated significant improvement in faint-end performance. The 16x mode was subsequently commissioned in November 2020 and is now available for general use. 16x mode is being used routinely for NGS fainter than R~11, and down to R>15, This observer information page has been fully updated with the current results of re-commissioning and details of the upgraded system. Further details on the measured/expected performance of these modes is available below. Other important details relevant to observation planning since the WFS upgrade can be found in the Expected Overhead section.
Overview
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 (NGS) in proximity to the science target.
2022B Call for Proposals
PALM-3000 will be available for PHARO science and private instrument observations in 2022B.
Instruments Status
- PALM-3000 is fully operational and supported by Palomar staff. Wavefront correction in 64x has demonstrated performance in the range of 120-140 nm RMS wavefront error (equivalent to K-Strehl = 88%), 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 91% K-Strehl, corresponding to 105 nm RMS (July 2014).
The current performance of 160nm RMS has been demonstrated in 64x with V = 8 guide stars, which does approximately meet the design specification. In November 2019 P3K 's wavefront sensor (WFS) was upgraded to an OCAM2k EM-CCD camera with sub-electron read-noise. Peak performance on bright (V<8) guide stars has not yet exceeded that seen with the pre-upgrade system. However, for fainter NGS, 64x mode has shown comparable correction to what the pre-upgrade system achieved on guide stars two magnitudes brighter.
- Instrument Status:
- PHARO (public)
- Is currently operational at the summit.
- P1640 (decommissioned, PI: B. Oppenheimer, AMNH)
- Coronagraph + CAL is performing routine science in a large exoplanet imaging and spectroscopic survey.
- SDC (private; PI: G. Serabyn, JPL)
- Stellar Double Coronagraph, working with PALM-3000 since first light in May 2014.
- Fiber Nuller (private; PI: G. Serabyn, JPL)
- Initial FN tests with PALM-3000 successful in June 2012.
- TMAS (private; co-I's: R. Dekany, COO)
- First full-aperture visible-light AO successful 27 Sept 2012. Strategies for concurrent visible + NIR observations (using PHARO) are under continuing investigation.
- DARKNESS (private; PI: B. Mazin, UCSB)
- Development of energy-resolving MKID imager funded by NSF in Summer 2013. Successful first light demonstrated in August 2016.
- PARVI (semi-private; PI: G. Vasisht, JPL)
- PARVI is the Palomar Radial Velocity Instrument, a fiber-fed high-resolution spectrograph for precision radial velocity measurements of exoplanetary systems. PARVI is available for community use as of 2021B. Contact Gautam Vasisht (JPL) or Chas Beichman (IPAC) if considering a PARVI proposal.
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 2019 to November 2019 taken in median or better seeing conditions (1.2 or better Ks seeing) over 5 re-commissioning nights. 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 ~75%. 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. A stable lock has been achieved on targets as faint as mV=16.2 in this mode during median conditions. Data are shown against the pre-upgrade engineering data with the old WFS (CCD50 data), demonstrating that the upgraded 64x mode delivers comparable performance to pre-upgrade performance in all subaperture modes (e.g. 64x, 32x, 8x).
- s16 pupil sampling mode: Larger (32.5 cm) subapertures
- The 16x mode was commissioned in November 2020, with general use beginning immediately after.
- Theoretical performance curves for 64x vs. 16x are provided below.
- Note that 16x mode is expected to extend faint end performance beyond 64x mode by 2 magnitudes once it is optimized, out-performing 64x for NGS fainter than ~mV=11.
- November 2020 commissioning data below shows 16x only matching 64x performance. Improvements to 16x mode in 2021B, boosted performance to the expected levels, surpassing 64x performance for targets fainter than mV~10.
Measured Performance of P3K OCAM upgrade vs. CCD50 (pre-upgrade)
![Ks_strehl_OCAMvCCD50.png Ks_strehl_OCAMvCCD50.png](https://www.oir.caltech.edu/twiki_oir/pub/Palomar/Palm3000/ProposerInfo/Ks_strehl_OCAMvCCD50.png)
64x and 16x Commissioning data vs. Theoretical Performance curves:
Expected System Capabilities
For 2020B, PALM-3000 will support natural guide star wavefront sensing in the following correction modes:
Number of subapertures per pupil diameter |
WFS limiting mag |
WFS best performance mag |
Notes |
64 |
V < 16 |
V < 11 |
|
16 |
V<18 (?) |
|
Available beginning in 2021A |
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.
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:
* Assumptions
- 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 2022B, 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.
Following the delivery of the WFS upgrade in November 2019, an increase in WFS flexure had been observed, with a sudden degradation in WFS performance when crossing the meridian. This flexure issue was traced to a loose translation stage and the problem was corrected in May 2021. For 2022B, observing overheads can again be expected to follow the normal timing described above without special care to location on sky or crossing of meridian.
Closed-loop AO image dithering on PHARO is expected to be functional at a level equal to or better than the prior PALAO 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 PALAO. These results are being quantified.
Wide-field astrometry
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.
Extended objects
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") and Neptune (shown below; V~8 and diameter ~ 2.3"). Contact the PALM-3000 PI for further information.
Contact information
Technical inquiries for specific observing proposals not addressed here can be referred to Principal Investigator, Richard Dekany at Caltech Optical Observatories or P3K Cognizant Engineer, Jenny Roberts at JPL (jennifer.e.roberts@jpl.nasa.gov).
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