ryan.crouch@LIGO.ORG - posted 12:01, Thursday 16 October 2025 - last comment - 11:29, Thursday 23 October 2025(87515)
OPS Thursday DAY shift update
18:45 UTC While Jim was running a measurement on ISI HAM5, SUS ITMY started to flash its' red Rocker Switch Death on L2 and report that its' L2 OSEMs were in fault, we also noticed there's a big new line at ~92Hz. Jeff turned off feedback from L2. It looks like it could be a sat amp issue, the L2 sat amp was upgraded this past Tuesday alog87469. Jeff is starting to work on characterizing a sat amp box in the EE shop to swap in.
We would need a lockloss to swap this component.
We are going to try to go back into Observing for a bit until we can fix it or lose lock.
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19:31 UTC Observing
FYI -- we went into observing with the ITMY PUM sat amp OSEM PD's still dead. We turned OFF the ITMY L2 (PUM) to R0 "damping" feedback loop, so the failed sensors *should* not have any impact on the IFO. However, an obvious, loud ~92-93 Hz feature remained new and glaringly obvious in the DARM sensitivity.
@DetChar / @CW Group Probably best to just veto this observation stretch, unless we -- in the future -- find some amazingly exceptional event.
2025-10-16 19:31 UTC to 19:54 UTC.
ITMY L2 (PUM) Sat Amp S1100148 installed on 10/14/2025. Replaced on 10/16/2024 with S1100080.
https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=87469