IFO is in NLN and OBSERVING since 00:46 UTC (2 hr 25 min lock)

Lock Acquisition and Issues with PRMI Locking

While locking, we would only lock PRMI for a 5-10 seconds before it would lose lock (not complete lock, just PRMI). Interestingly, the same wiggly behavior was seen in the multiple PRMI locklosses (Screenshot 1). Trending LSC loops more generally (there was mention of movement before our last lockloss), there seens to have been motion in PRCL and MICH 5 seconds before the PRMI lockloss. In the 9s that this particular screenshot’s PRMI lock held, there was an oscillation seen in MICH OUTand more strongly in PRCL IN (screenshot 2). No clue if this is relevant but it seems to have happened before the PRMI lockloss so may have caused it.

Seeing that the input channels had notably more fluctuation in the signal, I checked the SRCL INand MICH IN and noticed that the LSC MICH IN signal was the loudest, getting a strange kick that seems to have led into the PRMI lock but got worse as time passed. Screenshot 3 illustrates this.

After 10 or so locklosses in PRMI, we lost total lock and interestingly, upon re-locking, this issue did NOT occur. I trended the LSC behavior during the DRMI lock (which was quickly successful and didn’t actually go through PRMI) and no LSC kicks were present. This leads me to think that there may be something exacerbating the PRMI locking and relocking (in the LSC loops) that does not affect the DRMI locking maybe?

Or maybe this is just a red herring and these loops always run for PRMI locking only but were a tad more aggressive in this alignment configuration so needed a total lockloss to “try again”.

SDF Diffs

Per Jennie’s direction, accepted SDF diffs that corrected previously accepted incorrect sdf diffs (screenshot 4).

Log:

00:39 UTC - Reached NLN

00:46 UTC - IFO is OBSERVING