Reports until 12:04, Thursday 25 May 2023
H1 ISC
sheila.dwyer@LIGO.ORG - posted 12:04, Thursday 25 May 2023 - last comment - 11:43, Thursday 01 June 2023(69907)
relaigning ISCT1

Sheila, Ryan S, TJ

This morning we continued the ISCT1 and PR3 alignment from 699036989769857

TJ reverted the X arm green references to what they were yesterday morning, seen snapshot here, and re-ran intial alignment of the X arm.  Ryan S and I went to ISCT1 and saw that the beatnotes weren't well aligned, but the whole table alignment was better than what TJ and I found yesterday.  We toggled PR3 between 151.6 and 148.5 yaw slider, and saw that the ISCT1 alignment was sort of close to OK for both of these, such that beams were clearing their appertures and making it to the diodes they should have without clipping. 

This means that after our table realignment yesterday, the table was in a sort of OK alignment (beams not totally missing their optics) for 4 configurations: both of the green arm alignment set points and both the PR3 pointings.  This means that the table alignment that TJ and I did yesterday fixed some gross misalignment that wasn't due to either of those things, (it has been a long time previously since the alignment on table was fixed up). 

From the control room TJ, Ryan and I, with PR3 set to 148.5 yaw slider (setting for locks yesterday), adjusted PR2 to lock the X arm in IR, ran the WFS for INPUT align, and did a MICH bright alignment.  Ryan and I returned to the table and moved the bottom periscope mirror to improve the alignment of the Y beam onto the trans diode, which allowed TJ to lock the Y arm in green and run inital alignment for that.  In the meantime, Ryan and I adjusted the position of the X trans diode, and improved the COMM beatnote using the beatnote BS and the one upstream of it in the X arm path.  We eneded up with a COMM beatnote of 6dBm, which drifted down later when TJ re-ran inital alignment for the X arm and is now at -1dBm. 

After TJ finished the Y arm green inital alignment, and a MICH bright alignment, Ryan and I realinged the DIFF beatnote, which is now -7dBm.  TJ then completed the intial alignment steps we had skipped (PRC and SRC) and is now trying to lock DRMI.

Comments related to this report
sheila.dwyer@LIGO.ORG - 16:02, Thursday 25 May 2023 (69911)

After struggling with poor PRMI buildups, we realized that there was a typo this morning in the camera offsets, so TJ redid the initial alignment with the offsets from yesterday morning.  Then Ryan and I went to ISCT1 and realigned the beatnotes, which were already close but not good enough for locking.  Now TJ has finished the initial alignment and we are going to attempt locking again.

sheila.dwyer@LIGO.ORG - 20:36, Thursday 25 May 2023 (69918)

Both TJ and Corey had difficulty doing INPUT ALIGN, with Corey just now we found that it would lock once I reset the POP 45 I dark offset to -72, which was consistent with last night.  I've hard coded that into the guardian, so that it's for now not averaging the dark offset each time the whitening changes but just being set to -72.  With this INPUT_ALIGN was able to run and get the X arm transmission to 1. Corey is doing the rest of IR alignment.

jeffrey.kissel@LIGO.ORG - 17:55, Friday 26 May 2023 (69944)
In the end this PR3 and ISCT1 alignment was not needed. The problem was that the HAM-ISIs were all drifting off in Yaw (RZ) slowly, but surely, for weeks -- see LHO:69934.