Figure 1. Yesterday we had two hours of data with the interferometer locked in LN2. The intereferometer looks stable during that period, the increase in fluctuation happens only in LN3 when SR is misaligned. The sideband gains (B4 12MHz mag and B4 112MHz mag signals) start to fluctate much more. The BS TY input error signal and the local control also increase in fluctuations. It could be an effect or a cause of the sideband gain fluctuations.Fi

Figure 2. Compared to a month ago in LN2 (on Oct 7) the dark fringe has 70% more power (0.025 instead of 0.015 on B1p PD2), and the sensitivity is worse by 5Mpc.  

18:09 UTC As a simple diagnostic I started EDB OMC scans in LN2, did not
make a realignment, so I am just hoping it has remained good enough
after one month. The scan parameters are the same as in previous EDB
OMC scans: frequency 0.002Hz, amplitude 0.5 degree, offset 23.27
degree

20:07 UTC stopped EDB OMC scan

Figure 3. Compared to old scans (figure 1 of https://logbook.virgo-gw.eu/virgo/?r=67382,) the power of order 2, 3, 5, 6, 8 is about double what it was back in July. While the power of mode orders 4 and 7 is almost the same, the mode 9 is a factor ~1.5 higher. I don't know if that tell us anything more than the total power on B1p being higher, but I am surprised that two out of eight modes remain the same, while others go up significantly.

/users/mwas/OMC/EDB_OMC_fast_scan_20251110/EDB_OMC_fast_scan.m