We are leaving the interferometer locked for the night to see how things are stable over night.
The BS IM stage is engaged for the longitudinal control with the cross over between the IM and TM stages set to 0.1 Hz.
The attached is a screenshot of the trend of various signals when the Michelson was in lock last night.
The lock lasted in total lasted 2-ish hours. In the middle of the stretch, I engaged the IM stage as written in the main entry. 40 minutes later, after the engagement of the IM stage, the lock ended. Seemingly this was due to the degraded interferometer alignment since the fluctuation of the error signal kept decreasing as a function of time.
However, looking at the optical lever signals, I didn't find any suspicious large drift in IMMTs, IMMTT_TRANS, PRs, BS or ETMs. Note that PR2, BS and ETMs were servoed to an operation point.
