Received phone call at 1:20amPDT.
Saw that H1 was at NLN, and ready to go to Observing, but could not due to SDF Diffs for LSC & SUSETMY (see attached screenshot):
1) LSC
- H1:IMC-MCL_FM_TRIG_THRESH_ON at 100 (should be 1300)
- H1:IMC-MCL_FM_TRIG_THRESH_ON at 90 (should be 200)
I was not familiar with these channels, so I went through the exercise of trying to find their medm, but for the life of me I could not get there! The closest I got was LSC Overview / IMC-MCL Filter Bank, but they were not on that medm. (probably spent 30min looking everywhere and in between with no luck). Looked at these channels in ndscope & these channels were at their nominals for the last lock. Also looked in the alog, and only saw SDF entries for them from 2019 & 2020. Ultimately, I just decided to do a REVERT (and luckily, H1 did not lose lock).
2) SUSETMY
- This was just a TRAMP, so I also REVERTed this.
Then H1 automatically went back to Observe.
Maybe Guardian, for some reason took these channels to these settings? At any rate, going to try to go back to sleep since it has been an hour already (hopefully this does not happen for the next lock!).
These MCL trigger thresholds come from the IMC_LOCK Guardian and are set in the 'DOWN' and 'MOVE_TO_OFFLINE' states.
In 'DOWN', the trigger ON and trigger OFF thresholds are set at 1300 and 200, respectively, for the IMC to prepare to lock as seen in the setpoints from Corey's screenshot.
In 'MOVE_TO_OFFLINE', the trigger ON and trigger OFF thresholds are set at 100 and 90, respectively (for <4W input), as seen in the EPICS values from Corey's screenshot.
So, it would seem that after the lower thresholds were set when taking the IMC offline sometime recently, they were incorrectly accepted in SDF. I'll accept them as the correct values in the OBSERVE.snap table once H1 is back up to low noise, as I expect they'll show up as a difference again.