I compared the spectrum with better sensitivity (blue, 9th 12:35:00) and worse sensitivity (red, 9th 17:35:00), as shown in Fig.1.
From the Fig.1., here are clear excess in 50 - 300 Hz.
That structure sometimes appeared from the tidal effect (reported in klog32674)
So I checked several signals.
Fig.2. showed the time series of several channels at last night.
The K1:VIS-ETMX_IP_ISC2LVDT_L_OUT channel was already reached the limit value, so after that time, the tidal effect would be suppressed by MN actuator.
We don't know why tidal effect affect to the sensitivity curve when controlled by the MN actuator, that effect would be clear.
(Continuous large value output made several circuit noise??) Changing the coil driver would be one choice (but during observation???)
Even in the observation period, this kind of frequent variation of the sensitivity may cause non-usable data, which would be equal to not observing. From this viewpoint, It might be nice to adjust the actuator gain or whatever to effectively widen the actuator range.