oli.patane@LIGO.ORG - posted 07:40, Thursday 23 October 2025 - last comment - 12:33, Thursday 23 October 2025(87679)
Ops Day Shift Start
TITLE: 10/23 Day Shift: 1430-2330 UTC (0730-1630 PST), all times posted in UTC
STATE of H1: Corrective Maintenance
OUTGOING OPERATOR: Ibrahim
CURRENT ENVIRONMENT:
SEI_ENV state: CALM
Wind: 6mph Gusts, 5mph 3min avg
Primary useism: 0.03 μm/s
Secondary useism: 0.39 μm/s
QUICK SUMMARY:
IFO was in IDLE when I got in due to issues last night with a high EY Roll mode. I just started an initial alignment so we can be further along in locking once commissioners arrive onsite.
Locking attempt 1 this morning: Locked to full power, Oli ran the asc high bandwidth script (userapps/isi/h1/scripts/revert_asc.py) premptively to avoid having problems with the 1 Hz ring up.
The last thing this script does is sets the LSC FF gains to 0, 45 seconds after this finished we had a sudden large increase in noise first at 300 Hz in DARM (ETMX ESD) and DHARD then 0.1 second later in CHARD, which unlocked the IFO. This happened in the close beam diverters state, but is probably not related to the beam diverters. This is a different problem than what we've been seeing overnight.
No gains or anything else in the CHARD or DHARD filter banks were changed in those 45 seconds either, which rules out some other rogue change
Elenna and I commented out the DHARD boost from low noise ASC, because it takes 45 degrees of phase at 1Hz and so leaving it off may help our improve our 1Hz problems. This boost was added to improve the stationarity of SRCL to DARM coupling by reducing the DAHRD RMS 77857. We are leaving it off for now because we can probably go to observing without it if we can stay locked.
Next locking attempt we sat for over an hour at full power, without doing the LOWNOISE ASC step.
We had ETMY saturations when we ran through the ESD transitions, and they continued after DARM was switched, until Elenna turned off LSC FF. When we turned the feedforward back on ETMY didn't start saturating. However, at the time that the PRCL and SRCL feedforward came on, the roll mode started ringing up. We lost lock a few minutes into this ring up, but the amplitude was much smaller than the locklosses from this mode overnight (about a factor of 100 lower).
We aren't sure if the roll mode was the cause of the lockloss or not.