J. Kissel, P. Thomas

We tried using settings in the Violin Mode Table to damp what the table says to be 1009.44 ETMY(?) violin mode that has rung up by 2 orders of magnitude in recent lock stretches. Those settings are to use MODE9 bank, with FM1 (1008.45-1009.02), FM4 (100dB), gain = +100. Unfortunately, no success (as gauged by exponential reduction of control signal out of the bank) once past the initial turn of of the filter. Also tried 
- moving the phase of the filter +/- 60 deg with FM2 or FM3, but nothing budged. 
- the filter specifically targeted for 1009.44 Hz in that bank (FM10), but no phase around the unit circle caused an improvement.

We would have explored further, but LLO was up and running, so we punted by accepting the settings in the OBSERVE SDF to have the Violin Mode Table settings (FM1 (1008.45-1009.02), FM4 (100dB), gain = +100 -- where it was entire OFF before -- in hopes that something might happen for the better in the long run. (Continuing to watch as I write this log indicates still no change, though).

This has not been coded into guardian or anything, so the filter bank gain will be zeroed upon the next lock loss, and show up as a DIFF in the H1 SUS ETMY SDF once we get to OBSERVE. We should accept having it OFF.

I attach an ASD of the mode. Pink is from Oct 18th (some good reference time, nothing special), Black is when I got started this evening, and Red is where has ended up after attacking it. No change.