J. Kissel, E. Hall

Worried that the 1083.7 Hz calibration line on PCAL EY -- the "standard candle" for the > 1kHz roaming calibration line on PCAL EX -- is being swamped by new non-stationary noise around 1.1 kHz, I took a closer look. I've compared the DARM ASD (0.01 Hz BW, 10 avgs) and coherence between PCALY RX PD and DARM at several different times:
     2016-01-30 22:22:27 UTC -- Canonical O1 Reference Time, with no such new noise (Shown in YELLOW)
     2016-10-31 07:00:00 UTC -- Beginning of last night's quiet, long lock stretch (Shown in PURPLE)
     2016-10-31 10:00:00 UTC -- In the middle of the same long lock stretch, when the range degraded a little bit (Shown in BLUE)
     2016-10-21 17:30:00 UTC -- Toward the end of the ghoulish lock stretch with high microseism, high-wind, and an 5.4 [mag] earthquake. (Shown in NAVY)

One can see that, regardless of the non-stationary noise, we can still get ample coherence between PCAL and DARM with 10 averages and a 100 [sec] FFT. Recall, this 1083 Hz line is *not* used in any of the calculations for time-dependent DARM loop parameters, so we're free to use any bandwidth and integration time we wish to get the best coherence / SNR/ uncertainty. As such, we'll just leave the line where it is.

*phew*!