[Murakoshi(Aogaku) , Yuzurihara]

We started the lockloss investigation on 2025/02/10. The other plots are summarized in wiki.

Seismic motion with f>=1Hz

After the strong seismic motion with the frequeycn more than 1Hz, most of suspensions started to oscillation and lockloss occurred.

• 2025-02-10 14:19:50 UTC, GPS: 1423232408 (1403 s) [Fig] [Fig]
• 2025-02-10 17:19:45 UTC, GPS: 1423243203 (6306 s) [Fig] [Fig]

Oscillation with 1 Hz

We observed the oscillation with 1 Hz in K1:ASC-MICH_IN1_DQ, K1:VIS-ITMY_TM_WIT_P_DQ, K1:VIS-ETMY_TM_WIT_P_DQ, K1:LSC-MICH_IN1_DQ, and channels related to ASC arm. The amplitude was growing until the lockloss.
As chated with Kenta-san, this oscilltion seem to have came from the ITMY pitch. It's better to prepare the damping filter.

• 2025-02-10 14:59:14 UTC, GPS: 1423234772 (1506s) [Fig]
  • At 2.8 sec before the lockloss, we observed the glitch in K1:OMC-TRANS_DC_A_IN1_DQ. [Fig]
• 2025-02-10 21:56:33 UTC, GPS: 1423259811 (2340 s)
• 2025-02-10 22:37:52 UTC, GPS: 1423262290 (1775 s) [Fig] [Fig]

Under investigation

Following two lockloss, we couldn't find the obvious phenomena related to the lockloss. The cause is still under the investigation.

• 2025-02-10 13:17:22 UTC, GPS=1423228660 (1255 s)
• 2025-02-10 20:56:00 UTC, GPS: 1423256178 (12379 s)
  • If the interferometer was locklos for long time, the tidal effect might affect keeping the lock status. The related filter was turned off in the morning 2/12. [klog]