elenna.capote@LIGO.ORG - posted 09:36, Monday 11 March 2024 - last comment - 12:11, Monday 11 March 2024(76241)
Clipping on IM4 trans
We are clipping on IM4 trans. I trended the position of IMs 1-3 over the past few months and it appears they moved significantly from their position before and after the vent. The t1 marker on these plots marks the approximate time that the positions changed which corresponds to the end of O4a and the start of the vent.
As a note, this means our PRG channel is untrustworthy right now.
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The location mons on Hepi and the ISI suggest that thos have not moved, but IM4 pitch has a large shift.
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I trended the IM4 trans beam position and NSUM along with the IMC input power. The overall pitch position in IM4 trans has changed significantly, and the NSUM value in lock for the same 60W of PSL input power has dropped from 57.4 to 54.4.
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