Reports until 23:06, Friday 24 August 2018
H1 DetChar (DetChar)
sheila.dwyer@LIGO.ORG - posted 23:06, Friday 24 August 2018 - last comment - 10:13, Monday 27 August 2018(43654)
Violin mode request

We have a request for some DetChar help.

We would like a high resolution (better than 1mHz) resolution measurement of the frequencies of a pair of our violin modes.  They are at about 501.624-501.625 Hz and 501.628-501.629 Hz.  This will help us design damping filters for them that can be well centered on the mode we are trying to damp without ringing up the nearby neighbor mode.  It might be easier to resolve the two frequencies by finding time stretches where one mode is rung up more than the other and vice versa (like they are here)

Some times that might be useful are:

 

Comments related to this report
keith.riles@LIGO.ORG - 11:54, Sunday 26 August 2018 (43664)DetChar
Link 

I'm not sure how helpful the attached plots are, but they show averaged spectra (inverse noise weighting) from four epochs using the daily 1800-s Fscan SFTs Greg has generated that are fully contained during the times suggested:

24aug2018-A - 1.5 hours from Aug 24 00:00 to Aug 24 1:30 UTC
24aug2018-B - 2.5 hours from Aug 24 03:30 to Aug 24 6:00 UTC
24aug2018-AB - 4.0 hours from A and B together
25aug2018 - 4.0 hours from Aug 25 02:00:00 to Aug 25 06:00 UTC (not DC readout)

Overlain spectra are shown for the bands 
500-520 Hz
501.5-501.8 Hz
501.62-501.64 Hz

To aid further exploration of other modes, the Matlab fig file (300 MB) from which the zooms were produced can be found at
https://ldas-jobs.ligo.caltech.edu/~keithr/ViolinModes_H1_24-25Aug2018.fig
Images attached to this comment
gabriele.vajente@LIGO.ORG - 10:13, Monday 27 August 2018 (43671)DetChar, ISC
Link

See also 43670 for a high resolution (0.2 mHz) PSD around the modes.