This is a continuation of the results reported in 23331 adding this time the Q measurements for the 2nd Harmonic of the violin modes for ITMX and ITMY suspensions. Based on the 10 hours of data from (UTC) 2015-11-04 06:35:00 to (UTC) 2015-11-04 16:15:00 when the damping filters for these harmonics were turned off.

I attach the spectrum of the 10 hours of data with resolution of 1mHz and 68 averages, in red are the peak frequencies identified here as 2nd harmonics for ITMX and ITMY and these are the ones I track here with a line tracker (iWave).

Attached are the summary plots for the line tracker locked modes; at the top is the frequency as a function of time and at the bottom is the Log of the amplitude as a function of time. A first order polynomial is fitted to Log(Amp) in order to obtain the Q of that mode.

In comparison with n 23331 this time we observe many more modes with a clear ringdown allowing for more accurate measurements of Q as shown next:

            Frequency                       Q                Delta_Q

   1.0e+09 *
   0.000000991746043   0.638343205424020   0.000149585967453
   0.000000991932780   0.988513060431184   0.000433659978759
   0.000000992424650                   0                   0
   0.000000992793647   1.544250594114285   0.000442769972986
   0.000000994277692   1.846260247611300   0.000357683597242
   0.000000994646171   1.429803598985770   0.001138277433661
   0.000000994733913                   0                   0
   0.000000994897934   1.363257521653677   0.000632572972344
   0.000000995365554   1.412623504284980   0.001169331947625
   0.000000995645184   1.427802427814187   0.000897711718659
   0.000000996250457                   0                   0
   0.000000996528556   1.051941151626503   0.000247088823712
   0.000000997717925                   0                   0
   0.000000997887934   1.367480640577778   0.000256968037986
   0.000000998664500                   0                   0
   0.000000998805575   1.414837156915169   0.000225767863446