So, I checked the lock loss reason.
For the ID=1202 lock loss event,
First we found the GRY trans power was reduced before ~250 ms from the locked loss (1.0 -> 0.9) as shown in Fig.1. and OMC DCPDs saturated, then, locked loss happened.
So, I focused on the ETMY suspension signals.
Fig.2. showed the several channels for the ETMY, then I found the MN oplev pitch jumped about 3 urad without changing the oplev SUM value.
(Previously, we found the oplev SUM jump generated the MN oplev glitch, but in this case we cannot see the oplev SUM jump)
I didn't know the reason why MN oplev pitch jumped, the reason of locked loss may come from here.
I also checked the PS MN pitch, PS IM pitch and TM oplev pitch, no significant jump can be seen.
Fig.3. showed the several ASC signals, after the -250 usec in horizontal axis, several DoF started drifting.
We don't know all locked loss event were caused by this reason, but we continued to check the lock loss last night.
ETMY MN oplev pitch glitch (sometimes w/, sometimes w/o jumping of TILT oplev SUM)
ETMY suspension drifted
ASC feedback became strong (break the balance?)
Fluctuation of the OMC DCPD appeared in ~12 Hz
OMC DCPD saturated
AS0 cross and/or control break.
Lock loss
From the klog, I can find the one activity klog33930.
There are possibility to improve the situation by performing the temperature adjustment.
