Alexa, Kiwamu,

We tried the DRMI tonight with the arm cavities held at a off resonance by ALSs. No exciting result yet.  

(Too high speed in DRMI)

We could lock the DRMI only twice and they did not last for more than a couple of minutes. According to the band-limited RMS plots in the control room, we are having a monontonically increasing micro-seismic tonight, starting 10 hours ago. (Presumably) due to the high seismic, the DRMI fringe tonight is much faster than usual.

(ESD-UIM crossover issue)

Also we experienced an issue in which the ESD-UIM had a bad cross-over. When we closed ALS DIFF, it stayed locked fine for the first 10 minutes or so. But we noticed that the DARM feedabck was slowly developing a 1-ish Hz oscillation which gradually started using up the ESD range. This eventaully caused saturation in either or both of the ESDs and we lost the lock. In order to avoid this issuem. we tried decreasing the ESD LOCK_L gain from 1 to 0.8 on both ETMX and ETMY. This reduced the amplitude of the oscillation and also the in-loop spectrum got back to how it had been. We are concluding that the cross-over between UIM and ESD changed from yesterday.

After adjusting the ESD gain, ALS DIFF reliably stayed locked for a long time, typically order of 20 minutes. Each lock ends usually due to misalignment in ETMX or ETMY.

(ETMX ESD check)

This is just an observation of ETMX ESD.

In the process of checking the ESDs and etc, we checked the reponse of the ESD in the pitch direction by shaking it at 4.1 Hz and looking at it with oplev. We noticed that shaking it in pitch mostly gave us yaw. Shaking yaw gave a good yaw motion though.  We checked ETMY and it was not the case.