TMS Meeting Minutes, October 7, 2021

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

  • Data from 2021.10.03 looks good (available on the Drive)
  • Passive mode data acquisition with continuous elevation changes (tracking object), and jumps (switching object)
  • There was some active correction by TMS at the very start of the night (recovering starting position)
    • However, during this experiment, it was realized that the last reference for TMS was taken during closed-dome testing, so the reference was not useful
  • Heejoo produced channel dropping plots showing which channels dropped and when they dropped
    • Many channels filtered out by std. dev. filter when changing targets
    • Previously, there were a couple of channels that had an elevated likelihood of dropping
    • However, it seems that this has been corrected, as the channels now have relatively even dropping counts
    • Andrew suggests looking further into cases were channels drop when the optics are NOT moving (we expect channels to drop when the optics are moving)
    • Interesting spot to look at is around 0400 UT, then changed targets, then there was a single bad correction around 0420 UT
  • John's plot shows all relevant information for the passive testing
    • John worries that there could be cases where a single channel drop could cause a bad correction
    • However, Andrew notes that we don't send a correction whenever we drop a channel
    • When at high elevation, there are very large errors in the pointing model at high elevation
    • puts in pointing corrections on the group (hub tilts)
    • TCS puts in pointing corrections on mode 2 (mount)
    • Note, LBC takes individual exposures and the guiding resets at each new exposures (not in between, because the shutter is closed)
    • The reference for guiding changes at each exposure
    • John is unsure as to why the discontinuities in guiding are so large (this is not expected)
  • Andrew reminds us that we would like to go back to redundant channel operation after the commissioning phase is finished, where we can dynamically adjust the number of used channels
    • Reminder of filtering: by looking at the previous two measurements and the current measurement, we can compute the standard deviation and drop channels if we exceed a specific threshold
  • Trenton has nearly completed the CAD model of the LBT primary mirror
  • There might be time for LBC coming up, according to Olga
    • Andrew suggests that, given our limited LBC time, we should take as much passive data as possible to make sure that the thermal correction is doing the right thing (particularly the sign of the focus correction)
    • Word of wisdom, make sure your wrongs have the right parity to cancel, particularly when making aspheres
-- TrentonBrendel - 07 Oct 2021
Topic revision: r1 - 08 Oct 2021, TrentonBrendel
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