Reports until 00:01, Tuesday 11 February 2014
H1 ISC
stefan.ballmer@LIGO.ORG - posted 00:01, Tuesday 11 February 2014 - last comment - 00:59, Tuesday 11 February 2014(9967)
PR3 drifted

Sheila, Kiwamu, Stefan

For the green team: The green beam needs to be realigned on ISCT1 because we had to move PR3.

We noticed that the maximum green arm transmitted light had dropped significantly (from 830 cts to about 500 cts) over the past day.

Also when we locked the PRMI on sidebands, we noticed that the POP18 buildup had dropped from 24000cts tp 4000cts. Looking at the in-vac POP QPDs we found that the actual build-up didn't drop significantly. Thus we suspected clipping, and indeed the green beam was on the edge of the first iris on the table. We moved PR3 to (P:-237.328, Y:-257.276) to center the beam on the iris. Indeed, when we locked up PRMI again we were back at 24000cts.

The old slider values were (P:-240.328, Y:-252.276), so we moved 3urad in pit, and 5urad in yaw.

Comments related to this report
stefan.ballmer@LIGO.ORG - 00:59, Tuesday 11 February 2014 (9968)
Link 

We looked at how much of a jump the PR3 move was on the witness sensors and the optical levers
                     old           new     delta
Witness sensor P:   -311.8        -307.2    +4.6
Optical lever  P:     26.2          28.6    +2.4
Alignment slider P: -240.328     -237.328   +3.0

Witness sensor Y:   -214.9        -220.0    -5.1
Optical lever  Y:     23.4          19.4    -4.0
Alignment slider Y: -252.276     -257.276   -5.0

All are supposed to be urad...

The witness sensors are the least reliable, they seem to drift on the order of 5urad over hours. But it's not clear to me that any of those signals are predictive of what we saw.

Attached is also a 30day trend of all those signals.
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