J. Kissel

Now that we have updated EPICs records that store the DARM loop model (LHO aLOG 29992), I wanted to confirm the Nutsinee's recent 15 Mpc BNS range gain (LHO aLOG 30085)was not because the calibration of the DARM response was changing. I've confirmed the gain is not because the calibration has changed. I also wanted to sanity check the new DARM model parameter time dependence channels (LHO aLOG 29855). I'm sure if I trust them yet; we still need a comparison against offline calculations of the same thing (aka "SLM Tool").

See all of the attachments.
Plot (2) -- Recreates her picture of the BNS range trend over 24 hours. Note that the two times I compare are shown with vertical lines on the dataviewer trace in 
   - red (1159272420, Sep 30 2016 12:06:43 UTC, Sep 30 2016 05:06:43 PDT) and in 
   - magneta (1159270000, Sep 30 2016 11:26:23 UTC, Sep 30 2016 04:26:23 PDT).

Plot (1) -- Recreates her ASD, at the above mentioned times. This shows the full spectrum, and the drastic difference in noise performance between the two times.

Plot (3) -- This shows the same ASD comparison, but zoomed in around the calibration line frequencies, all generated by PCALY, and read out in the calibrated reflected PD, or RXPD. This qualitatively shows that there's very little change in the line heights at any of the line frequencies.

Plot (4) -- This shows the magnitude and phase of the transfer function between PCAL and DELTA L EXTERNAL in (m/m) around the low frequency calibration lines; 7.93 and 36.7 [Hz]. At the calibration line frequencies, we can see a change of at most 5% and 3 [deg]. This is about the uncertainty in the overall calibration anyways (though this has not yet been officially quantified for the current state of the instrument). This is encouraging, with respect to the SRC detuning optical spring -- whatever detung we have appears to be unimpacted by these alignment changes. A *much* more rigorous study than two points of one lock stretch should be done, however.

Plot (5) -- Same as plot 5, but for the high frequency calibration lines; 331.9 and 1083.7 Hz. We see similarly little change in these magnitudes and phases.

Plots (6-9) -- These show trends of the optical gain, cavity pole, and the actuation strength of the QUAD compared against the BNS range over the 4 hour period in which Nutsinee was playing. While there is a clear correlation between the cavity pole and optical gain against the BNS range, I'm not sure I believe that the cavity pole has changed by 30 [Hz] given such little change in magnitude and phase of the 331.9 [Hz] line. Again, a *much* more rigorous, offline comparison should be done between these values which are calculated from the calibration line amplitudes and phases.