State of H1: Observing at 159Mpc
Very quiet shift with H1 observing the entire time except at 03:25 UTC when SQZ unlocked (SQZ_OPO_LR Guardian reported "PZT voltage limits exceeded"). Guardians were able to bring everything back automatically and observing was resumed within 2 minutes. BNS range improved by 5-6Mpc after this event.
We have a checker in SQZ_MAMNGER to relock the OPO if the PZT is not in 50-110V range when IFO is down to prevent this. The PZt changed too fast for this checker to help though, probably caused by a 0.4degF LVEA temperature change in zone 4 at the time.
The range increase appears to be because the SQZ angle was in a bad place before relock (220 degrees rather than nominal 180), see attached. Unsure if we expect the OPO PZT changing to effect SQZ angle.
This may be improved by moving the ADF closer to where we want to optimize (200Hz?). Currently the ADF at 1.3kHz but best range is with SQZ not optimized at 1.3kHz 75151. There could be two zero ADF servo crossings at 1.3kHz, one with good 300Hz SQZ and one with bad 300Hz SQZ and sometimes the servo takes us to the wrong one.
Attached is DARM before and after this relock.
