19:39 H1 lost lock to no obvious cause. Jeff K seized the opportunity to take charge measurements he wasn't able to yesterday. the LLO operator was informed of this activity. They, too, will do some opportunistic work in the interim.
20:57 I needed to re-align the green arms.
21:11 Begin main locking sequence.
22:00 chasing dow PI modes 28 and 26
22:06 Intention bit - Undisturbed 52Mpc
Interestingly, the lockloss is very proximal to the EndY Chiller fault but I can't say they are related.
I trended numerous PEM and ISI channels (some attached) and the CY_STATUS dropped from 1 to 0 at 19:38:37utc, the IFO dropped lock 19:39:29, and PUMPSTAT alarmed at 19:39:40. There is a large MAINMON glitch when the CY_STATUS changed but no ground seismometer response at the time of lock loss. I'm not sure about the CY_STATUS relation to the PUMPSTAT. I stepped through the spectra of the floor STS but see nothing in the broad stroke at which to dig deeper.