thomas.shaffer@LIGO.ORG - posted 16:00, Saturday 06 May 2017 - last comment - 07:47, Sunday 07 May 2017(36069)
Ops Day Shift Summary
TITLE: 05/06 Day Shift: 15:00-23:00 UTC (08:00-16:00 PST), all times posted in UTC
STATE of H1: Observing at 67Mpc
INCOMING OPERATOR: Jim
SHIFT SUMMARY: One liock loss for an unknown reason. The PSL seem to struggle and the FSS would lose lock repeatedly so bringing it back up took a bit longer than usual.
LOG:
- 21:14 Lock loss
- 22:39 Observing
This is pure speculation on my part but if the input modecleaner is swinging around for whatever reason - which means that it is pulling the laser frequency around - it might be that the injection locking of the oscillator may have saturated. Unfortunately there is no monitor of the saturation status of the SR560 that was added to the injection locking servo. But I have seen occasions where the system indicates that it is locked but the SR560 red indicator light is on. A trend of the oscillator PZT output, or of its injection locking status at the time(s) that the FSS is having a hard time might indicate this. The other reason might be that with the change of input modecleaner alignment, the alignment onto the second loop ISS photodiode array may also have changed.