TMS Meeting Minutes, December 2, 2021

Attendees: Andrew, Breann, Christian, Heejoo, John, Olga, Trenton, Yang (Zoom Meeting)

Recent TMS Operations:
  • Three operational nights recently (all passive)
  • LBC FWHM 20211129 plot from Christian sparked an interesting conversation
    • Olga noted that the LBCr FWHM around 10 UT showed substantial degradation
    • It has been determined that this was not a TMS error, as TMS was run in passive mode
    • TMS doesn't show spikes in X,Y,Z,Rx,Ry,Rz
    • There were a few images with elongated spots, relatively high FWHM around 10 UT
    • Elongation could be caused by optics positioning, optics shape, and mount tracking errors
    • Olga looked at the tech chip images to see if there was a possible error in the Z4 injection or otherwise and couldn't find anything amiss
    • Andrew notes that if we have an image quality question like this, we need to have TMS data, thermal data, and PSF data on hand to diagnose the problem
  • Andrew and Trenton will meet to discuss how we can streamline the data analysis and processing workflow, especially the thermal data analysis (action item for Trenton to make a meeting)
  • PSF variation across the LBCr focal plane has been attributed to waviness of the focal plane
  • To measure the surface morphology of the focal plane, Andrew suggests using the Etalon system to measure; able to resolve at the micron level
  • There are a variety of techniques that could be used to measure, including the superfoc images (superfoc has 60 micron steps); John thinks the stepping probe is about 10 microns
  • Olga reminds us that there are multiple contributing factors to the variation in PSF across the focal plane on LBCr images; may be possible to decompose tilts of the cryostat to surface morphology of the focal plane
Closed-Dome Test
  • TMS lasers shone through certain instrument
  • The basic finding from Olga is that there is no evidence of TMS lasers affecting measurements with LBCs or with MODS (though there may have been an LED on with MODS)
  • The purpose of this was to take a series of exposures and stacking, which is more like what most observers would do
  • Heejoo is wondering if we can turn on the TMS during flat exposures; John notes that flat exposures are only ~10 s
  • MODS, PEPSI, and LBC are the only instruments sensitive to H-band (around TMS operation waveband), so these are the ones we need to test for TMS stray light
  • 800 nm line in MODS appears to come from the data fiber inside of MODS near the CCD
  • This line also could come from the LBC data fiber
  • Archive for Stray light:
Last Night:
  • The system continues to work perfectly smoothly with no hitches and appears to be very user-friendly
  • Heejoo to work on data analysis soon
  • We are planning to try swapping the USB cable for the laser shutter to improve consistency of control; Leroy to swap soon
  • Once we confirm the shutter is successfully operating, we will begin leaving the TMS laser on for longevity of life
  • When using TMS to collimate at the start of the night, we have had great results
    • Residual thermal focus issues we haven't resolved, but we have not had an instance where coma has been out of spec
  • Andrew suggests that we consider producing a tailored database of start of the night FPIA runs with inclusion of thermal conditions and then match this with TMS data
  • Heejoo will place an order for some parts for fiber inspection and testing (checking for broken channels); Leroy assisting, again (Thanks, Leroy!)
  • We desire to have Z4 correction included in the S/W output
  • Thanks to Yang for all of his hard work on the software!
  • Yang notes that there were some merge issues on GitHub and the column headers were left off
  • John suggests that we call the thermal focus correction thermal_z4 in the tms.log file
  • Channel dropping strategy
    • So far, we haven't had much trouble with dropping
    • When we do have a problem, we have trouble using TMS until we obtain a new reference
    • The whole issue with pose acceleration drift is centering on the fact that it arises from smooth noise in individual collimator channels
    • A noise free set of data for a reference works forever, but when you add noise to the channels, you get results comparable to what we are seeing
    • Heejoo and Trenton to go up the mountain again soonish to help reset the collimator mount plates to minimize rocking
  • Currently, Ch. 10 and Ch. 11 are deliberately disabled b/c of dropping issues
Commissioning Document:
  • With continual additions of new data, we need to make some updates
  • Andrew to take an action item including the most recent results
  • Andrew remarks that one of the goals of the commissioning document is to make a centralized repository where observers and partners can go to understand what TMS really does
  • Christian notes that it would be really great to be able to compare the operation of TMS on one mirror versus the operation of FPIA on the other mirror; this could be super powerful for convincing astronomers to use TMS
  • We can give observers a concrete number on the marginal benefits of TMS, and convince them that they won't lose quality but rather improve
  • Consider running with active LBCr TMS and LBCb FPIA, then with active LBCb TMS and LBCr FPIA
  • Christian notes that this can be placed high on the priority list for engineering time in the coming weeks to validate and confirm that TMS can go into operational mode
  • Olga notes that we should really consider how to separate out thermal effects on one side versus the other; with all the data in hand, we can parse this out and explain why TMS works well and potentially better than FPIA
  • TMS really shines when you are changing elevation; with TMS, an FPIA run is not required upon elevation changes
Engineering Time:
  • Next opportunity is a short block in Dec. (12/28, 12/26), though there is high priority AO stuff that must get done, and then two nights in January
  • Christian to make sure there is a bit more engineering time
  • Olga has a question about putting in a TMS pointing/co-pointing model for LBC
    • There are plenty of cases where you would need to switch optics and slew
    • TMS pointing data would be GREAT to have and turn into a pointing model
    • Andrew argues that it would be useful to run with a newly developed pointing model using the recent TMS data (Dave Thompson, Olga Kuhn)
Topic revision: r2 - 04 Dec 2021, HeejoChoi
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