TRICK pages
TRICK is a near-infrared tip/tilt sensor (NIRTTS) for the Keck I
LGS-AO System. TT correction in the IR is better than TT
correction in the visible because the IR star is AO-corrected.
TRICK = Tip-tilt Removal
with Ir Compensation at Keck.
TRICK Facts
| Component |
Details |
| Location |
Dewar on K1AO bench |
| Detector |
Engineering grade H2RG |
| Operating Temp |
˜100 K |
| Filters |
Home, Blocking, Open, H, Ks |
| Dichroics |
H, K, H-annular |
Things to Consider
- Often the TRICK TT star is closer to the science target
- There are several use cases where the science target is either much
closer to TRICK TT star than the visual (STRAP) TT star or the
science target is the TRICK TT star.
- TRICK still needs a visual TT star for STRAP and the LBWFS
- We use STRAP to initially close the AO loops, then switch to
TRICK. The LBWFS is required for all LGS-AO targets.
- Using TRICK changes the AO calibration
- The act of inserting a TRICK dichroic into the beam adds
astigmatism to the image on OSIRIS. A TRICK-specific COG file must
be used. The AOAcq tool will load this COG at "Setup Bench"
- Using TRICK requires a different pointing origin
- TRICK dichroics and filters are TRICK-centric
-
| OSIRIS Science |
TRICK dichroic/filter |
Pointing Origin |
| K-band |
Hband/H |
H-OSPEC or H-OSIMG |
| Y-/J-/H-band |
Kband/Ks |
K-OSPEC or K-OSIMG |
- TRICK TT correction requires a closed DM loop
- The benefit of TRICK is that the IR TT star is AO-corrected.
There is no TT-only mode for TRICK. TRICK may lose the TT star
under the following conditions:
- Bad seeing → persistent poor AO correction
- AO hiccup → AO correction momentarily gets worse
- Dithers
- TRICK seems more impacted by thin clouds
- If you are struggling and suspect clouds, STRAP may be a better choice
Why TRICK?
The AO correction is noticeably better.
