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Detector Characterisation (Glitches)
robinet - 11:34 Thursday 19 September 2019 (46964) Print this report
Seismic glitches at low frequency

UPV shows that V1:ENV_WI_ACC_X is a good channel to veto low frequency glitches in h(t) (see plot). The dead-time is only 0.030 %.

I decided to use the UPV threshold to generate an online veto (as described in 46963). The veto channel is V1:DQ_Omicron_VETO_GENERIC_ENV_WI_ACC_X_2019-09-19-seismic.

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robinet - 11:43 Thursday 19 September 2019 (46965) Print this report

Another ENV channel identified by UPV targeting only higher frequency component of the seismic glitches: V1:ENV_IB_CT_ACC_X.

--> a veto channel will be generated (dead-time=0.005 %)

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robinet - 13:15 Thursday 19 September 2019 (46967) Print this report

For seismic noise hunters, let me post 2 glitch examples:

  1. The first one looks like an excited line @10.8 Hz. These glitches seem to be visible in VIM spectrograms: https://vim-online.virgo-gw.eu/resources/2019-09-18/resources/20190918_spectro_spectromedian_Hrec_hoft_20000Hz_0_30_604800.jpg
  2. The second example seem to be a different category of glitch. The disturbance is visible in both ENV_WI_ACC_X and ENV_IB_CT_ACC_X (are these probes co-located?). Moreover there is clearly some upconversion to h(t)
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fiori - 17:30 Thursday 19 September 2019 (46971) Print this report

The second example of seismic glitch looks associated to a sudden and pretty loud seismic transient covering 5Hz to 20hz detected by ENV seismic sensors almost everywere in CEB, Figure 1. No sound detected.

Figure 2 shows a map of sensor indicating the two sensors shown by florent in Omicron plots, they are not co-located.

Interesting to know the rate they occur and if there is some periodicity.

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