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Detector Characterisation (Broadband noise)
swinkels - 19:57 Monday 12 June 2017 (37972) Print this report
Helicopters again
Today, a helicopter was repeatedly flying low over the site, while making rounds for making practice landings at the local airport. Fig 1 shows it flying today over the technical building, while fig 2 is most likely the same one (registration GdF 220) in January above the canal right next to the Virgo site. As usual, it is our friends from the Guardia di Financia, which we have seen many times in the past. Fig 3 shows the usual Doppler pattern in the microphone of the central building, while 4 shows that BRMSMon seems to pick it up correctly.

The interferometer was not locked, so it is hard to estimate the influence on the dark fringe, but during a science run, this would have likely disqualified one hour of good data.
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swinkels - 16:49 Thursday 05 October 2017 (39684) Print this report
Someone still thinks it is a good idea to fly a helicopter next to a very sensitive experiment, even though the usual suspect should have been notified. This time, we were locked with a range around 25 Mpc, and unsurprisingly the noise is visible in hrec.
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fiori - 11:26 Friday 06 October 2017 (39691) Print this report

I played a bit with the helicopter data. Attached plot shows the footprint in accelerometers at PR blind flange, SPRB link, and also B4 beam, MICH and PRCL. Accelerometers also got significantly excited. The footprint in PRCL (better) B4 and MICH looks similar to what seen by DARM. I would suspect the noise is coupling as scattered light at PR.

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swinkels - 18:53 Thursday 08 November 2018 (43479) Print this report
We got another free acoustic noise injection yesterday afternoon, likely the Guardia di Finanzia doing their monthly training session. For the last of the fly-bys, the interferometer was just locked with a sensitivity of around 25 Mpc. The event seems to have happened just in between two injections for the mirror charging, so the data might be usable for noise studies. This time, I don't see any obvious noise in DARM, so this might show the coupling to acoustic noise is lower now than 1 year ago. Still, it would be good if we can ask them to stop doing this during O3.
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swinkels - 11:33 Monday 26 November 2018 (43745) Print this report
And again today, this needs to stop before O3.
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cieslar - 10:21 Tuesday 27 November 2018 (43768) Print this report

Just a spectrogram of the ENV_CEB_MIC channel for the fly-by (see Figure 1) reported in the entry 43745.

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