Title: 11/23 Eve Shift 24:00-8:00 UTC (8:00-16:00 PST). All times in UTC.
State of H1: Observing
Shift Summary: EX ISI is causing troubles again, but some changes to ASC seem to be keeping things under control for now
Onsite Support: Evan, Jeff, Jenne
Activity log:
IFO was unlocked when I arrived. Evan and Jeff were trying to diagnose EX.
1:00 I start initial alignment, this is hampered by AlignIFO and IMC nodes not cooperating. IMC node seemed to hang and refuse to lock occasionally, I had to re-request Lock. Lock X-arm IR was also uncooperative.
2:40 Finally to NLN. Except for EX slowly ringing up and then down, all's quiet.
A few details on the Xarm locking, in case it's helpful for someone else in the future:
We had the XARM gain turned up to 0.15 (which many people have been doing lately, when the Xarm is being fussy (nominal is 0.05)), however when it would catch lock, it would oscillate significantly. I think this was because the optical gain was too low (highest flashes and average transmission were about 0.8), and so we couldn't afford the 2 integrators that come on immediately after the lock is acquired. I had Jim disable the filter module triggering (by setting FM1 and FM2 of the XARM to "Man" rather than "Trig"), and we were easily able to acquire a smooth lock. After a few seconds the ASC brought the arm power to just above 1.0, and we switched the triggering settings back to normal. Alternatively, we probably could have turned the XARM gain up even higher, to make sure we weren't so close to the low edge of the phase bubble, but there didn't seem to be a reason to explore this more thoroughly.