Plot attached shows that the violin peak at 998.828Hz, ITMY Mode 18, was damped overnight with a gain of +300.  The nearby peak at 998.961Hz, ITMY Mode 17, was not rung up.

Attachments:

1. spectra: left peak is IY mode18, right peak is IY mode 17,
   • left plot: REF(green) 25 Nov 2019, cursor values (magenta) 31 Dec 2019
   • right plot: REF(green) 25 Nov 2019, cursor values (red) 8 Jan 2020
2. overnight trends:
   • top plot: IY mode18 gain and drive
   • middle plot: IY mode18 monitor filter (polluted by mode17)
   • bottom plot: IY mode17 monitor filter (polluted by mode18)
3. trends since Oct 2019:
   • top plot: IY mode18 gain and drive - mostly zero, not damped
   • middle plot: IY mode18 monitor filter (polluted by mode17) - shows the mode peak increasing over the 2 or so months since the October break
   • bottom plot: IY mode17 monitor filter (polluted by mode18)