jeffrey.kissel@LIGO.ORG - posted 13:43, Friday 18 November 2016 - last comment - 15:33, Friday 18 November 2016(31610)
1083.7 Hz CAL Line Turned OFF Temporarily
J. Kissel There's been renewed excitement about the relationship between the 1083.7 Hz calibration line and the surrounding, non-stationary PSL intensity/jitter noise coupling into the sensitivity. Namely, DetChar has seen glitching "around the 1 kHz calibration line." I had looked at this relationship briefly a few moons ago (see LHO aLOG 31035) and concluded these features were unrelated, and did not impact the use of the 1083.7 Hz line due to the intensity/jitter noise's convenient double-peak shape. I had thought I'd run an on/off test during that study, but rather than dig up the history, I find it easier to just run a new on/off test. As such, I've turned OFF the 1083.7 Hz calibration line at Nov 18 2016 21:33:40 UTC, Nov 18 2016 13:33:40 PST, GPS 1163540037. If we survive the EQ that's now hitting as I type this aLOG, I'll leave it OFF for an hour or two.
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The attached plot shows that the noisy behavior around the frequency of this line persists after it was turned off.
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1083.7 Hz calibration line restored just after the lock loss at 2016-11-18 23:30 UTC.