YuhangZhao - 14:45, Tuesday 16 March 2021 (2399)
Mirror drift again on 20210316 due to earthquake
On Japanese standard time 04:56 JST 16 Mar. 2021, an earthquake happened close to Tokyo area. (attached figure one)
I checked the oplev signal during this time in the saved data of DGS. PR, input and end mirrors reached the maximum of oplev sensing range. Besides, this oscillation lasted for almost 20 seconds and the exponential decay lasted for almost 40 seconds. (attached figure two)
After the earthquake, all mirrors drifted away from their original position. (attached figure three)
| Yaw_original position | Yaw_new position | Pitch_original position | Pitch_new position | |
| PR | 150 | 320 | 500 | -2000 |
| BS | -120 | -90 | -1200 | -1700 |
| Input | 3200 | 3200 | 500 | -2000 |
| End | -900 | -1700 | -1200 | 3500 |
According to the above table, we are going to move picomotor to recover mirror position.
Before moving picomotor, I also checked the spectrum of all mirrors pitch/yaw. No touching induced peaks were found. (attached figure four)
Images attached to this report
