Since the last maintenance, it appears to be some excess noise at high frequencies (>3000 Hz), along with a prominent wide peak between 2440 and 2520 Hz. While this does not significantly impact the BNS range or searches, I am investigating the source by running a high-frequency BruCo analysis (the standard BruCo on VIM, with its 2 kHz downsampling rate, may not be sufficient for this).
I’ll post any new findings as soon as they become available.
This is a known and somewhat expected side effect of the work done yesterday during the Maintenance on the Slave Laser of PSL; more precise information will come to the logbook, for the time being you can find some explanation in slide 8 of commissioning discussion from this morning's meeting.
Thanks Diego for the quick explanation.
I report (for confirmation) that the channels found to be most coherent are those linked to the SSFS (V1:SSFS_Corr_50kHz), which have high coherence both with the broadband trend and with the peak at 2500 Hz.
Other channels with interesting coherence are the magnetometers in the central building with a structure at 4000 Hz. I don't know if this structure was already known too.
The quantity in brackets in Figure 3 is the average coherence in the 2900 and 4100 Hz range, used to rank the most coherent channels
