M6.5 Malaysian & M7.0 New Zealand EQs Kept H1 Down For Almost 8hrs. Once SEI_ENV went from EARTHQUAKE to CALM:
- Ran an alignment and everything was fairly smooth getting back to OBSERVING.
- Violins were a little elevated (but still on the FOM DARM--just above 1e-15).
- Hung out at OMC WHITENING 22min before going to NLN.
- Had a couple ETMx SUS diffs (from alog 86027, see ACCEPTED SDFs for this change to possibly address the ETMX Glitch locklosses)
Then went to OBSERVING finally.....but less than 5-min later, H1 had a lockloss.
This lockloss is distinctively due to the same yaw ASC issue we've been having lately (see 85973 for example).
The following lockloss, that Corey hasn't had a chance to report yet, has a different behavior where the ASC oscillates for a minute or two before the lockloss. However, I see the same behavior in the TSMX osems I do for the above locklosses, which is that suddenly the F1, F2, and F3 osems see a large motion and doesn't seem to be present in the master outs. However, this lockloss seems to have a few of these large motions that cause CSOFT Y (and therefore other ASC loops) to ring down momentarily before it happens again. I see these "kicks" happen twice before the lockloss. As a reminder, the TMSX suspensions are adjusted to center the beam on the TMS QPDs for the SOFT loop feedback, so kick in the TMS suspension will likely kick the SOFT ASC which is highly cross coupled to other loops.
The attachment shows the "kicking" behavior in the TMSX osems.
