Since the NCal electronics have remained on since GPS=1258930068 (Wed Nov 27 22:47:30 UTC 2019), see LHO aLOG 53524, I have taken the weekly Fscan averages from the summary pages to look for any additional noise from spectral artifacts. Granted, this is not a conclusive study to confirm or vindicate any couplings caused by NCal, but it is a first look at long duration averages and suggests we should investigate this further. I would also suggest that it's worth turning off the Ncal as long as it does not remain an essential tool for IFO operations. Past experiences indicate that all non-essential electronics should be disconnected during observing runs. This suggestion is, at the moment, due to an abundance of caution regarding new, non-essential IFO operations electronics connected during an observing run.

Below I attach three ratios of the weekly Fscan averages of H1:GDS-CALIB_STRAIN in the 10-100 Hz band, a common region for noise lines from electronics.
Figure 1: ratio of Fscan weekly average Nov. 3-10 / Nov. 17-25
Figure 2: ratio of Fscan weekly average Nov. 10-17 / Nov. 17-25
Figure 3: ratio of Fscan weekly average Nov. 25-30 / Nov. 17-25 <-- NCal electronics remain on from Nov. 27

In the two weeks preceding the Ncal being left on, the Fscan ratios show some variations, as indicated by the ratio deviating from a nominal (unchanged) value of 1.0. These variations are below a maximum ratio value of 20 (one line only). See figures 1 and 2. However, the final figure shows the change from the week the NCal electronics remain on and many lines show large ratio values up to maximum values greater than 50.

Further study is needed to determine if this really is caused by the NCal electronics remaining on since Nov. 27. At the moment, I'd suggest turning the electronics off and possibly disconnecting as well to be fully cautious.