thomas.shaffer@LIGO.ORG - posted 01:25, Wednesday 30 July 2025 - last comment - 17:03, Wednesday 30 July 2025(86095)
Ops Owl Update
Looks like the first attempt at locking after the ground motion settled enough failed at find IR. I was notified, but we should change this to start an initial aligment first.
- Started initial alignment, couldn't find IR for input alignment.
- Restored IMs back to osem positions before the earthquake
- SRY wouldn't lock and even tripped SRM. Moved SRM in P & Y to get better flashes.
- Then another earthquake rolled through, though not huge, it delayed locking for a bit.
- Reset H1_MANAGER and IFO_NOTIFY, we'll see if it can bring us back on its own.
These aftershocks just keep coming!
Had a decent attempt at DRMI and PRMI before this latest one rolled thorugh, but it just wouldn't catch. After another initial alignment, where I had to touch SRM again to get SRY to lock, we're ready to another lock attempt. The ground is still moving a bit though, so I'll try to be patient.
DRMI has locked a few times but we can't seem to make it too far after now. While the ground motion seems to have finally gone away, the FSS isn't locking. Looks like the TPD voltage is lower than where we want, but maybe thats just because it's unlocked?
After futzing with it for 40min it eventually locked after I gave the autolocker a break for ~10min. I actually forgot to turn it back on while I was digging through alogs, but that did the trick!
Another seismon warning of incoming aftershock.
DRMI just locked again! Looks like it's moving on well now so I'll set H1_MANAGER back up.
Re: FSS issues, Ryan S. and I have been having a chat about this. From what we can tell the FSS was oscillating pretty wildly during this period, see the attached trends that Ryan put together of different FSS signals during this time. We do not know what caused this oscillation. The FSS autolocker is bouncing between states 2 and 3 (left center plot), an indication of the loop oscillating, which is also seen in the PC_MON (upper center plot) and FAST_MON (center center plot) signals. The autolocker was doing its own gain changing during this time as well (upper right plot), but this isn't enough to clear a really bad loop oscillation. The usual cure for this is to manually lower the FSS Fast and Common gains to the lowest slider value of -10 and wait for the oscillation to clear (it usually clears pretty quickly), then slowly raise them back to their normal values (usually in 1dB increments); there is an FSS guardian node that does this, but we have specifically stopped it from doing this during RefCav lock acquisition as it has a tendency to delay RefCav locking (the autolocker and the guardian node aren't very friendly with each other).
In the future, should this happen again try manually lowering the FSS gain sliders (found on the FSS MEDM screen under the PSL tab on the Sitemap) to their minimum and wait a little bit. If this doesn't clear the oscillation then contact either myself or Ryan S. for further assistance.