For a while this morning I wrote down times that I saw glitches, whether or not they saturated the ESD, that looked similar to me to the glitches that we gete when we have fast locklosses. It would be helpful if Team DetChar could look around to see if there are other channels that see the glitch, that could help us understand what is going on and where the glitch is coming from. A hypothesis is that this could be a family of similar-looking glitches that sometimes cause lockloss, and sometimes don't. But, since these fast locklosses are one of our big limitations to how long the H1 IFO can stay locked, we need to figure them out.
Times are in UTC on 24 Oct 2018, glitches happened within 1 minute prior.
14:52 (This one I looked at very briefly - it's at 1224427963-0.18 sec. I see a small glitch in DARM_OUT and in the EX ESD)
15:01, 15:08, 15:13, 15:13 later in the same minute, 15:15, 15:17, 15:42, 15:58, somewhere btwn 16:04-16:07 there is a glitch, 16:27, 17:56, 18:13
At 18:14 we had a lockloss, and it could have been one of our mysterious fast ones, which could just be a larger version of this family.
I'll look more into this tomorrow if no one from DetChar is available.
Thanks for pointing to these glitch times, Jenne! Just to let you know, a few of us from DetChar have started looking into them, and we'll hopefully have more to report tomorrow.
I took a look for glitches in a 2 minute window around the times Jenne points out. Since most of the times Jenne posted pointed to obvious loud glitches, that's what I started looking for. I couldn't find anything similar to this for around 15:08, 15:13 and 15:15 though. For the rest of the times I found rather loud glitches, however they don't all look the same. Most are clearly overflows (if you just look at the spectrograms). Below I list the times of the glitches I found, and if an overflow which model it points to (sorry I'm rubbish at parsing simulink). I got the overflow information from the summary pages:
1224427963.30 - overflow in 98 2_0,3 (UR and LR ETMY L2 coil) and 88 3_1-4 (all quadrants of ETMX ESDs)
1224428469.55 - overflow in 98 2_0,3 (UR and LR ETMY L2 coil) 88 3_1-4 (all quadrants of ETMX ESDs), 10 0_12,13 (LSC) and 8 0_12,13 (OMC length dithers)
1224429544.87
1224430949.50 - overflow in 88 3_1-4 (all quadrants of ETMX ESDs)
1224431938.35 - overflow in 88 3_1-4 (all quadrants of ETMX ESDs)
1224432254.1 - overflow in 8 2_18 (OMC)
1224432439.6
1224433667.31 - overflow in 98 2_0-3 (all quadrants of ETMY L2 coils) and 88 3_1-4 (all quadrants of ETMX ESDs)
1224439031.89 - overflow in 98 2_0-3 (all quadrants of ETMY L2 coils) 88 3_1-4 (all quadrants of ETMX ESDs), 10 0_12,13 (LSC) and 8 0_12,13 (OMC length dithers)
1224440021.65 - overflow pretty much everywhere. This is ~63 seconds before a lockloss (98 2_0-3 (SUSETMY), 88 2_0-3, 88 3_1-4 (SUSETMX), 30 2_0-4 (SUSITMY), 29 2_4-9 (SUSITMX), 19 1_8-15, 19 24-31 (ASC), 10 0_7 (LSC), 8 0_7 (OMC)