[Kyohei W. and Kiwamu I.]

 There was a concern that the actuation coefficient of the VCO --- which actuates the PSL laser frequency via the refcav for the IMC locking --- were calibrated wrong and hence we might have kept plotting more-or-less inaccurate noise budget. Indeed the coefficient was underestimated by approximately 34% according to a measurement we did today. Giacomo helped us out by confirming that the coefficient had been indeed miscalibrated [1]. Of course this brings our past noise budget of IMC_F slightly higher, but certainly this is not a major issue.
 
 The measured VCO coefficient is 268302 Hz/V (see the attached figure made by Kyohei). Please use this number hereafter.

 A good news is that our measured value agrees with that of Livingston, which is about 246 kHz [2], within 9%. Our measurement was done by applying various DC offset at the input of the VCO box (2-pin lemo) and by looking at the frequency of one of the two outputs with a frequency counter. The input of the VCO box is designed to be a differential input and hence the x-axis of the plot is Vpos-Vneg.

[1] LHO alog #5534 Comments on "IMC noise"
[2] LLO alog #4645 "low range VCO installed"