camilla.compton@LIGO.ORG - posted 14:44, Friday 26 May 2023 - last comment - 17:48, Friday 26 May 2023(69930)
PR Suspension alignment over last weeks.
AM control room team: RyanS, TJ, Sheila, Keita, Vicky...
Trended alignment of PRM, PR2, PR3 over last 2 weeks. It is unusual to change PR3 alignment but recently we've had to touching PR3 to get PRMI locked (69751, 69917, 69924, 69903): 3urad in last 2 weeks. Top right pink trace attached.
Sheila noted that the the POPAIR and ALS (green) beat notes were reducing and then being brought back by PR3 moves (1st t-cursor). ALS beatnote realigning on ISCT1 in last 2 days (2nd t cursor, alogs 69897, 69897) brought back green comm/diff beat notes but not POPAIR. Sheila/Keita/Vicky noted this suggests something common on the green + IR path is drifting.
For newer information including HAM yaw motion, see TJ's alog 69924 .
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The problem was that the HAM-ISIs were all drifting off in Yaw (RZ) slowly, but surely, for weeks -- see LHO:69934.