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Reports until 17:15, Friday 12 September 2025
H1 ISC (IOO, OpsInfo)
elenna.capote@LIGO.ORG - posted 17:15, Friday 12 September 2025 (86893)
Failing to lock- possible issues with ASC

We have been trying to lock the IFO since we reduced the IMC REFL power. DRMI locking has been causing lots of trouble. First time we locked DRMI quickly, but then as the ASC engaged it pulled the buildups away and I couldn't turn off the ASC fast enough before a lockloss occurred. Then, locking DRMI and PRMI starting talking a very long time, 30 minutes or more. Sheila and I tried turning off the DRMI ASC except the beamsplitter. Then, Ryan S touched up the rest of the DRMI alignment by hand. We made it to ENGAGE ASC FOR FULL IFO, but then as the ASC engaged again the POP 18 buildup started dropping, and then we saw large glitches in all the signals- LSC and ASC, then lockloss. We don't know what caused the issues in full IFO ASC, but it seems similar to the DRMI issue- for whatever reason the ASC is not working properly.

We would like to go back to PREP ASC FOR FULL IFO and slowly engage the ASC by hand to figure out what's going wrong. But DRMI locking is still taking 30 minutes or more, and our recent attempt even the beamsplitter ASC didn't work properly. I think it's safe to say we won't be able to lock, let alone observe, for a while. Even if we could solve these ASC issues, we still need to get to laser noise suppression and check various things to ensure the IMC and ISS loops are working properly, we have the right amount of laser power, no significant glitches or degradations, etc.

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