Abstract
Oplev light was almost lost at 21:58 (11000ct -> 100ct on TILT_SUM).
IM_OSEM_V1_OUT_DQ showed 100um change from the last time when PR3 in SAFE (if it's calibrated).
Details
For the safety all the suspensions are in the SAFE mode now.
I compared current readout values of local sensors to ones in the last time when PR3 in SAFE (it's maintenance day on 4/28).
Figure 1 shows the time trend of all local sensors in recent 10 days.
As shown in the guardian STATE_N in the most right panel in the bottom column, PR3 is in SAFE (STATE_N=1) now (t=0).
And also it was also in SAFE at t=-8h (the last maintenance day).
Because of the drift in this week due to environmental changes such as the room temperature drift,
I'm not sure that we can directly compared current readout value to ones in 8days ago.
But at least sum of TILT Oplev decreased from ~11000ct to ~100ct (the 2nd left panel in the bottom column in Fig.1),
and IM_OSEM_V1_OUT_DQ shows ~100um changes from the last time when PR3 was in SAFE (the most right panel in the 3rd column).
Other sensors also shows o(10um) changes. But these changes are not so large compared with ones on PR2 as shown in Fig.2.
For your reference, TILT Oplev didn't lose light in PR2 and OSEM readout didn't show o(100um) change.
(The tanel order is same as Fig.1.)
On PR3, oplev light was lost when the 2nd time of occurring large EQ (seismic intensity is 5 at 21:58 JST yesterday) as shown in Fig.3.
Anyway, the recovering work should be done carefully.
Thank you for the check and we need to do CAREFUL recovery works. Maybe firstly check the on-site situation by eye-balls (like where the oplev beam spot on the QPD?) without doing any random changes.
In Fig. 1, PR3 LEN SUM seems ok, so the LEN QPD would be still illuminated. Hope not a big tragedy. PR3 tilt sum might show some kind of free swinging; note that PR3 suspension is now also at SAFE state.
Fig. 2 is the timing when the PR3 tilt oplev sum jumped; as noted in the original post by Yamamoto-san, this was not the first shook of the series of the large earthquakes.
