TMS Meeting Minutes, March 31, 2022

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

Trenton was encountering severe network dropouts, so these notes are a bit disjointed.

Opening Remarks:
  • Lots of focus build up on LBC Red, plus Z22 evolution
  • Andrew notes that the Z22 evolution can only be caused by thermal effects
  • There are some questions as to whether we can actually
  • Olga: "You have a pupil with a combination of aberrations, Z22, Z11, etc. How will you compare this against your model?"
  • Andrew argues that updates to the thermal model has the possibility to really improve FPIA
  • Q. from Olga: On engineering night, if we have the telescope in equilibrium, what if we could inject known offsets in Z22 and Z11 and see the response.
  • Interesting finding on March 28th UT
    • It was not possible to collimate at the start of the night (took hours)
    • At the top of the chip, they had round spots that looked kind of like trefoil
    • Steep temperature dropping chip
    • However, they went back much later in the night and they were able to get much better images
    • The thermal gradients are similar during both of these two cases
    • Andrew requests that Olga send over the data for this night for him to analyze
  • Best nights to extract Zernikes are when we are running VFAST extra throughout the night
Telemtry Spikes:
  • Seems more common near the horizon, and happens about every 1 to 2 hours
  • There also appear to be issues with the mirror reaching the limits at the start of the night when the TMS reference offsets are applied
  • It is possible that this is caused by having a different number of collimators available than were used to construct the reference
  • Temperature just causes a relative mispositioning of the mirror to the hub, so it shouldn't cause the mirror to run to the limits
  • Andrew has only seen channel dropping to cause the issues we have been seeing with large perturbations in the mirror (he notes this could also be caused by a whole lot of uncorrelated noise)
  • "The power bumps have demonstrated their wonderful ability to mis-collimate all the TMS collimators at once." - Andrew
  • There is the possibility that an abrupt bump such as a mirror drop could cause a large amount of uncorrelated noise across the channels
  • What if we had a funny thermal gradient in the LBC swing arm which caused enough of a twist in the hub to induce a substantial amount of motion in the primary mirror, as sensed by TMS
  • On March 27th, pointing was off by 55 arcsec on Red and 52 arcsec on Blue
Engineering Time:
  • There may be time tomorrow, but it could be taken
  • There are also possibilities on the 7th and 8th of April

-- TrentonBrendel - 31 Mar 2022
Topic revision: r1 - 01 Apr 2022, TrentonBrendel
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