Andy, Laura, Dr. Dan Hoak Something went wrong with the Pcal Y. It's not clear right now whether these were causing the glitches in ETMY, or whether there's a more general electrical failure at EY. The Beckhoff seems to have failed at 5:45 UTC (alog). At that time, we see the PCAL Y lines suddenly disappear, and this is obvious in DARM (first plot) as well as the PCAL Y photodiodes (plots 2 and 3). There are bursts of noise in the TX channel seen by the summary page spectrogram (plot 4), but shorter spectrograms of TX and RX don't show anything at times when we know DARM was glitching (plots 5 and 6). We'll continue to investigate.
Seems like pcal was gone somewhat after Beckhoff. A big DARM glitch came almost exactly at the same time as the Pcal power loss at 05:44:07.91, which was somewhat after beckhoff communication loss (1st attachment). Right after that glitch DARM became 2Hz-rich.
In the second plot, you can see that AOM drive, Pcal receiver and transmitter went away at the same time. Since there was no light, Pcal cannot be the cause of 2Hz thing. It's still possible that the loss of Beckhof was somehow responsible.
I checked mainsmon at EY though I don't know what exactly these are monitoring. I don't see mainsmon glitch when pcal was lost (2nd attachment middle), though it does glitch once in a while, e.g. t~440. This is through 60Hz and 180Hz band stop.
