[Sheila, Kiwamu]
Sheila had a difficulty in relocking the IMC. So I looked into it to figure out what is happening and fixed it by steering the PZT pit.
It was apparently due to a misalginment, mainly in pitch according to the GigE views. Looking at one-day trend, I found that the PZT pit suddenly had changed its value from 400 to -240 counts at around 8:20 am local. A mysterious point is that , after the PZT jumped, the IMC was still able to lock itself for approximately 4 hours.Then it ran into a situation where it was not able to hit the LSC trigger. I didn't see a significant drift in any of the MC suspensions. I fixed it by steering the pitch of PZT back to +300 counts. It relocked right away and we ran the offload script so that it doesn't loose the good alignment by a unclok. We should keep our eyes on this PZT.
The attached is the one day trend.
I changed the PZT offsets this morning to account for the temperature drop in the laser room over night. Robert then increased the nominal, so it is expected that the alignment shifts back towards the older settings. The correct way is to use the centroid of the reflected beam when not locked and steer the PZT to the same position. Dave added theses channels to the frame, so they can be trended (if you can figure out how they are named). We probably should add an error condition to the IMC locker which checks this at the beginning.