Virgo Logbook

Virgo Runs (O4b)

menzione - 14:50 Friday 17 January 2025 (65995)

Operator Report - Morning shift

ITF found in LOW_NOISE_3 in SCIENCE mode.
Under request of C. Fabozzi, In agreement with Run and Commissioner coordinators, at 09:51 UTC I set ITF in ADJUSTING mode in order to allow the passage of a truck trailer with excavator around the central area (north direction) at a walking step.
Unfortunately it caused the ITF unlock and the opening of SPRB_SBE loop. Properly closed via VPM.
After the unlock Ruggi performed a COMMISSIONING activity moving end mirrors ~3 mm, with ITF in LOCKED_ARMS_IR. Acivity concluded at 10:50 UTC.
Wind activity increasing (fig1). Relocking in progress, BAD_WEATHER mode set.

In this weather conditions ITF reached LN3 without particulary difficults but it also unlocks without particulary difficults...

Sub-system reports

SBE
10:29 UTC - SQB2_SBE loop opened due to the misalignment of vertical position. Recovered via stepping motors.
DMS reports a residual drift of horizontal actuators so I left the horizontal loop opened.
Expert informed.

Images attached to this report

65995_1737109359_20250117112010_mean_ENV__METEO_WE_WIND_SPD_30 (1).png

65995_1737121435_Screenshot from 2025-01-17 14-43-37.png

65995_1737121438_Screenshot from 2025-01-17 14-43-00.png

Comments to this report:

mwas - 16:40 Friday 17 January 2025 (65996)

The unlock around at 9:58 UTC may not have been caused by the truck trailer and excavtor but by the sudden increase in wind speed.

Figure 1 shows that in the preceeding 20 minutes there were two steps in SR alignment. These are usually caused by saturation of B1 photodiodes audio signals, which spoils the dither based SR alignment signals, causing a kick in the SR alignment. Usually after a few kicks like these during bad weather the interferometer unlocks.

Images attached to this comment

65996_1737128239_Screenshot from 2025-01-17 15-37-11.png

bersanetti - 17:56 Friday 17 January 2025 (65998)

During the ~30 minutes before the unlock we had the B1 PDs saturating in several occasions, causing SR and Range glitches (with the average wind speed not changing dramatically). However, only at the very end (when the truck moved around CEB) we can see a sharp increase in the seismometers' signals, and the corresponding large increase in the F0 corrections on the CEB suspensions; the PR and BS ones saturated right before the unlock (Figure and zoom).

Images attached to this comment