jenne.driggers@LIGO.ORG - posted 12:30, Thursday 28 March 2019 - last comment - 06:06, Friday 29 March 2019(47987)
IMC VCO sweep, zoomed in on non-whistle region
I have started another, somewhat slower IMC VCO sweep, in the frequency region around 78.8 MHz. Andy's plot in alog 47970 indicates that this is our best candidate for a whistle-free region.
I started moving the offset slider at about 19:16:50 UTC to get my starting place where I wanted it, a little low of 78.8 MHz. Then at about 19:23:35 UTC I started the script.
Picking upper and lower limits of the clean region of Andy's plot by eye, I'm sweeping the VCO between 78.8 MHz (-3.37 V) and 78.95 MHz (-1.48 V).
As with last night, this is a very slow change, and today we should be out of the whistle region for almost all of the sweep time, so we're leaving the IFO in Observing (with Keita's permission).
I've swept through the candidate VCO region once, and partially a second time. Since we've done a slow sweep in one direction, we're aborting the sweep-with-clean-data back in favor of some calibration measurements.
However, so that I don't accidentally cause any nasty glitches, I'm letting the VCO frequency continue to sweep, so anyone looking at the data will see that there is suddenly a lot of noise. Just stop looking at the data at around 21:21:00 UTC.
Also, by just looking at the DMT-Omega, it looks like there's definitely a major difference in the quantity of glitches reported as we sweep the frequency close to the edge of the clean region.
One sweep from -3V to -1.5V offset starts at 1237836061 and lasts for 4677 seconds.
VCO sweep started at 2019-03-28 12:23:37.922011 Pacific
VCO sweep ended at 2019-03-28 14:32:12.228220 Pacific (This is when I stopped the script - Cal injections started before this)
Also, Daniel looked at the glitch mon on the wall, and found that our cleanest region so far looks like it's when we're at -2.1 V. I have put us there, and then accepted that value in both the safe and observe snap files. The value is not monitored (maybe we should monitor it?!?), but at least now it'll come back to the correct value upon reboot.