Andy, Josh, Dan, 

We found (using the script described in 17791 and 18588) that some of the COMM channels (LSC-Y_COMM_CTRL_OUTPUT, LSC-X_COMM_CTRL_OUTPUT) used for tidal offload from the IMC were hitting their limits during some of the recent H1 locks. The attachments show: 

1) LSC-Y_COMM_CTRL_OUTPUT and LSC-X_COMM_CTRL_OUTPUT at the end of the first short observation intent time from the summary page today. Note, they are saturating at 10 um for this whole lock. 

2) Same channels for the end of the next lock, COMM tidal is not saturating during this lock. 

3) IMC-F during the lock when COMM tidal is saturating, note it is running away to very high values. 

4) IMC-F for the second lock, when COMM tidal isn't saturating.

Additionally, we see some additional noise during the first lock where COMM was saturated, and at those times DARM coherence with MCL, PRCL, and SRCL also increases. This may or may not be caused by the saturation, but we thought it worth reporting. 

5) Spectrogram of DARM during first lock. 

6) Coherence-o-gram of DARM vs MCL (note: a followup spectrogram indicates MCL got much noisier at the time with higher coherence) during first lock. 

Side note: We also saw ISI-GND_BRS_ETMX_RY_OUTPUT going between its limits, but Jeff says this is an out of loop tilt sensor, so we'll ignore it.