Kiwamu, Hang, Nutsinee
After we made some modification to the new lockloss tool (the modification was made on my copy, not the original), we started to investigate the time of ETMY saturations with it. I randomly picked seven glitches out of twenty listed by the saturation alarm. Three glitches caused the range to drop no more than 50 Mpc, four caused the range to drop below 10 Mpc.
Range dropped below 10 Mpc
| Time (UTC) | First optic to Saturate | Time before saturation alarm(second) | BNS Range (Mpc) | 2.5+ Mag Earthquake within 30 minutes before saturation time |
|
Sep7 01:30:45 |
ETMY L3 | 0.427 | 6 | None |
| Sep7 00:48:01 | ETMY L3 | 0.608 | 0.5 | 2.8M in Alaska, 00:18:41 UTC |
| Sep6 17:57:06 | ETMY L3 | 0.583 | 17 | None |
| Sep6 17:03:24 | PR3 M3 (LR and UL) | 3.543 | 3 | None |
Range dropped no more than 50 Mpc
| Time (UTC) | First optic to Saturate | Time before saturation alarm (second) | BNS Range (Mpc) | 2.5+ Mag Earthquake within 30 minutes before saturation time |
| Sep7 04:46:19 | ETMY L3 | 0.694 | 57 | 5.1M in Solomon Islands, 04:23:02 UTC |
| Sep6 19:45:34 | ETMY L3 | 0.053 | 52 | 3.0M in Dominican Rep, 19:22:59 UTC |
| Sep6 19:31:36 | ETMY L3 | 0.296 | 58 | 3.0M in Dominican Rep, 19:22:59 UTC |
Most of the chosen glitches look pretty much the same (low frequency fluctuation, glitch, then ring down) and don't tell us anything, accept that all three small glitches happened within 30 mininutes after an earthquake. However, I find the plots from Sep 6 17:03:24 particularly interesting. PR3 M3 glitched ~3 seconds before ETMY. Kiwamu thought this might shade some light on the mysterious ETMY glitches.
One thing I noticed is that quite many times the ETMY saturations happened at least half a second before the saturation alarm caught them. Why is that?
As for the plots, the blue is the data of channel indicated, red shaded area is the RMS, and the low, mid, high band are defined as:
low: f>0.25 Hz
mid: 16 Hz < f < 128 Hz
high: f>128 Hz (until Nyquist frequency)
I have also attached the list of channels I've looked into (basically all ST1 and ST2 ISI and all the SUS MASTER OUT DQ channels). There are SO MANY MORE glitches to be analyzed. In case anyone interested in helping I saved the modified code in /ligo/home/nutsinee.kijbunchoo/Templates/locklosses/python
