Ibrahim, Sheila, Elenna

We were having trouble in the "FIND IR" state, ans Sheila realized that it was due to the guardian thinking the x-arm alignment was poor. However, X arm had locked fine and Ibrahim had run the initial alignment. We asked Ibrahim to run it again, and noticed that it continued to lock the X arm green with a transmission of 0.6 (when it should be like 1). However, the convergence of the WFS and camera signals did not improve the arm alignment.

We saw that the COMM beatnote was also low, so I trended PR3 osems. The OSEMs show a few microradian movement in pitch and no movement in yaw. I tried moving PR3 pitch in the "right" direction according to the osems, but it only made the beatnote worse. Same moving in the opposite direction. Based on the ALS X camera, it looked like the beam was off in yaw, so I instead moved PR3 in yaw, which returned the beatnote to a good place and increased the X arm transmission to >1. So, we are baffled, but we trust our current table alignment so we are going to go with this PR3 placement. Overall, this is a 2 microradian movement in PR3 yaw to regain the beatnote/ALS X transmission.

The y cursor on the top plot shows the pitch position of PR3 two weeks ago when we originally aligned the table. There was not a significant change in PR3 yaw in the osem.