andrew.lundgren@LIGO.ORG - posted 15:44, Wednesday 07 June 2023 - last comment - 15:54, Wednesday 07 June 2023(70250)
52Hz peak in DARM
There's a peak in DARM around 52 Hz (with a second bump just below 50 Hz) that has come and gone in DARM the last few days. There's a noise source in the input optics mic that is in a similar frequency range. The noise in DARM could maybe be sidebands of the peak in the mic. The noise appears and disappears at some of the same times as in DARM, though the association is not that close.
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Beverly found that some of these times with reduced range also seem to have had excess ground motion at very low frequencies: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20230607/sei/ground_spectrograms_x/
Work is ongoing to see if this is related to that 51 Hz peak.