Operators name: Aoumi, K. Tanaka
Shift time: 16-24 (JST)

Summary:

Check Items:
VAC, CRY were no any problems

At 17:59, the value of the MCRACK thermometer suddenly dropped from about 20 degrees to 0  (fig. 1).

At 21:43, the value of the IYA FIELD thermometer raised 3 degrees and returned to the original value 10 minutes later (fig. 2).

16:00 OBSERVING from previous shift time

19:02 Lock loss due to earthquake at Noto peninsula (M3.9)

After an hour, it did not return to the observation state; according to the LSC_LOCK guardian, it did not go to the PRFPMI_RF_LOCK state but seemed to fail in the PRFPMI_IR_HANDOVER state, so we contacted an expert according to the manual. After an investigation with Ushiba-san, we found that the actuator of the PNC for Yarm was saturated and the control was not working (fig.3). However, the PRFPMI lock was automatically restored during the investigation, so we decided to maintain the current status quo.

20:44 Restore OBSERVING state (almost automatically)
24:00 keep OBSERVING state