I kept OBSERVATION state with OMC dither CLK of 30000 cnts to obtain better SNR OMC length residual motion signals.
Start time: 2025-04-29 05:30 UTC
Stop time: 2025-04-29 06:30 UTC

Figure 1 shows an example of spectrum of OMC error signals.
Calibration factor of 2e-11 m/cnt was used for the calibration as reported in klog33591.

Figure 2 shows the same spectrum with narrower frequency band (from 50Hz to 200Hz).
Though 100Hz large coupling from GND shaker to OMC length was reported (klog33586), 100Hz peak is much smaller than the others, so 100Hz peak would not be problematic at this moment.