Virgo Logbook

Detector Characterisation (General)

narnaud - 15:13 Monday 24 July 2017 (38797)

Big transient glitch in BNS range

One period from last night during which the BNS range showed a strong and few minutes long dip.

First figure: the glitch in the BNS range
Second figure: comparison of spectra: the black trace corresponds to the period of the glitch, while the two blue traces are reference periods taken 1 hour before and 1 hour after the glitch.

Images attached to this report

Comments to this report:

verkindt - 16:52 Monday 24 July 2017 (38801)

When looking at the exact GPS time of the glitch (1184818116.6934),
we can see that it covers a large frequency band up to 500 Hz.
Plot 1 shows the spectrogram of this glitch and a comparison
of the spectrum before and during the glitch.
It would be interesting to get its origin, but it is typically a glitch
which would be vetoed by the gating that was used in O1.

Images attached to this comment

narnaud, swinkels - 18:53 Monday 24 July 2017 (38805)

Time series of the glitch: hoft and LSC_DARM.

Images attached to this comment

swinkels - 21:49 Monday 24 July 2017 (38806)

The shape of the glitch seen in DARM is likely just the impulse response of the DARM loop, so this might be the result of a short strong glitch somewhere in that loop. This reminds a bit of some events on the mirrors themselves, but I could not find any clear excitation of any of the the drum or violin modes. I could only see the glitch in the DARM loop itself, and not in any of the other loops. It would be good to confirm this with an Omicron scan. It is not an Acl glitch.

narnaud, swinkels - 11:55 Tuesday 25 July 2017 (38817)

Here is the omicron scan: https://wwwcascina.virgo.infn.it/DataAnalysis/Omicron/narnaud/scans/1184818117_std. There is nothing striking in it.