TITLE: 10/31 Eve Shift: 2330-0500 UTC (1630-2200 PST), all times posted in UTC
STATE of H1: Observing at 147Mpc
INCOMING OPERATOR: Ryan S
SHIFT SUMMARY: Locked at 147 Mpc and have been Locked for 4.5 hours. Relocking today took a while due to a lockloss right after CLOSE_BEAM_DIVERTERS/beginning of OMC_WHITENING (87873). Coming back up was fine - I just went state-by-state from LASER_NOISE_SUPPRESSION onwards, and we were fine.
2.5 hours in is where it got interesting (87876). I noticed the DCPDs diverging. Since this happened yesterday (87842) and had been due to violin mode ETMX mode 6, I first turned the damping off for that mode since trying to damp the mode more yesterday made it ring up more. This clearly didn't help since the DCPDs started diverging at a faster rate, so I slowly upped the gain from its nominal of 5 up to 13. It seemed to work for a while - the DCPDs levelled out, but then the ETMX damp mode output started increasing again, this time parabolically, and the DCPD MIN and MAX's started wiggling. At this point I turned the gain back down to 9, but then the DCPDs started diverging again so I turned them back to 13. I tried no gain as well as nominal gain again, but DCPDs immediately start diverging. Here's a look at the relationship I was seeing with the damp gain, the damp output, and the DCPDs. I called Rahul. Eventually he decided to try turning off drive for ETMX mode 1 since it is at a similar freuqnecy, and that immediately fixed the problem. Currently he is looking into better settings, but otherwise he will leave damping off for both of them. So what happened yesterday ws probably that the guardian turned off ETMX mode 1, and that solved the problem.

LOG:

23:30UTC Relocking and in ADS_TO_CAMERAS
    - Had to turn on Hi ASC gain due to 1 Hz ringup
    - Lockloss after CLOSE_BEAM_DIVERTERS/start of OMC_WHITENING
    - Got up to LASER_NOISE_SUPPRESSION, waited
    - ADS_TO_CAMERAS, waited, turned on Hi ASC gain due to 1 Hz ringup, waited, went back to regular ASC gains
    - Stepped through each state individually and waited a few moments, nothing happened
00:38 NOMINAL_LOW_NOISE
    - 00:38 Observing
    - ~2.5 hours into the lock, DCPDs start divergingg
    - 04:49 Out of Observing to try and find better damping settings for ETMX mode 6
    - 04:58 Back into Observing
    - 04:59 Out of Observing to try and find better damping settings for ETMX mode 6/ 1