Started the day by running an initial alignment and relocking up to LOWNOISE_LENGTH_CONTROL with no issues along the way. Eventually spent 1hr 20min in this state and took a PUM/ESD crossover measurement using the template userapps/lsc/h1/templates/PUM_crossover_2024.xml, see attachment. Sheila confirms even with the lower coherence around the crossover frequency of 20 Hz, this is a good measurement and lines up well enough with the 2024 reference.

I then requested 'INCREASE_DARM_OFFSET' since that's where Ryan C. notes he started to see the ~9.8 Hz bounce modes start to ring up and waited. I soon started to see the ETM bounce modes (at least according to the monitors) increasing. I tried applying a damping gain of 1 on ETMX with the filters already set and saw a small response, but the mode was still increasing. Sheila suggested lowering the DARM offset to 7 from 10.75 to possibly give more time, so I did. Changing the ETMX damping gain around some more did affect the mode (especially turning it off), so it may be possible to damp these, but it's also very possible these filters are very outdated. I also transitioned to high-gain ASC between my damping gain steps of 1 and 2 and didn't see an appriciable change in the mode. I didn't get a chance to try many different settings on either ETM before we lost lock, and since the OMC DCPDs weren't close to saturating, lowering the DARM offset may not have helped after all. See ndscope screenshot for a summary of these attempts. The roll mode damping is still commented out in ISC_LOCK, so it never came on during all of this, but I never saw the mode increase at all.

On the next lock acquisition, I'll go slower after LOWNOISE_LENTH_CONTROL to see if I can get a better idea of where this ringup starts.