This morning, three transient noises, lasting several tens of seconds and limited to the 10-100 Hz frequency band, occured around 9h08 UTC, 9h38 UTC, 9h45 UTC.
Plot1 shows them in the spectrograms of LSC_DARM and Hrec_hoft_raw (on the same plot we can see also two 25' glitches).
Plot2 is a zoom on the third of those transient noises.
Are the transients corresponding to time that where outside of science mode during the same hour due to adjustments? See figure 1.
These should be nice scattered light injections from moving SWEB https://logbook.virgo-gw.eu/virgo/?r=63997. It would be nice if someone could confirm it by looking at the same spectrogram for DET_B8_DC, and also see if the frequency corresponds to the speed of the bench in the Z direction (along the beam).
Are the transients corresponding to time that where outside of science mode during the same hour due to adjustments?
Yes for the first two, not completely for the third transient -- see attached plot. Are there some guidances to assess when switching back to science after one such adjustment?
Transients are see also in DET B8 DC (Figure 1). Signal SBE_SWEB_F0_z_LVDT_500Hz converted into velocity and low pass filtered (fcut 0.5 Hz, in order to remove large high frequency noise in this signal) seems to reproduce sufficiently well the shape: Figure 2. Also the second order of arches (weakly seen in the photodiode) is similarly reproduced doubling the velocity, although not plotted. Maybe there is a better signal to use that measure the bench motion?
