related logbook: https://logbook.virgo-gw.eu/virgo/?r=69040
We measured magnetic field at WT 900m, where less instrumental noise is expected.
We used a portable setup with Bartington Mag-03 MC100 + Nanometrics Centaur.
These data; time series, ASDs, and spectrogram are plotted here. We can see the 1, 2, 3, ... Hz comb noise stationally.
(NOTE: Calibration should be confirmed)
Measurement continued through the Cascina holiday, and approximately 48 hours of data was stored.
I evaluated the ASD peak heights for the 1 Hz comb and 50 Hz power line hourly, and plotted their median, max, and min values.
To eliminate calibration uncertainty, the values are expressed in counts.
The median value of the 1 Hz peak was highly stable, whereas other metrics showed temporal variation.
