anthony.sanchez@LIGO.ORG - posted 13:13, Thursday 27 April 2023 - last comment - 16:56, Thursday 27 April 2023(69097)
Thursday Ops Mid Day Shift update!
Mid day Update!
Big Red was moved with out breaking lock!
IFO Status : Re-locking after a localized spike in ground motion caused a lockloss.
Issues relocking.... Lockloss at FIND_IR, Seesm like a very similar issue to last nights locking issues.
We are trying to resolve the issue, and relocking will commence.
The lock loss Tony mentions here seems to have been caused by some seismic event that was seen at all 3 VEAs. This is visible on the linked lock loss page, but I'm also including some trends. This burst was about 30s in length, and seemed mostly at higher fruquencies than we typically see in earthquakes. Time for the event was 18:59 utc.
On attached trends, left two plots are peakmon, which doesn't show much until after the lockloss seen by IMC-F. Whatever this was, it was big enough to get the SEI system to switch to earhquake mode (went over 1k nm/s on peakmon), but mostly after all the commotion. Middle two plots are the ITMY ground sensors and the X&Y sensor correction signals for the corner station ISI. RIght two plots are the end station ground signals and their beamline sensor corrections signals. These all show that the motion was seen and reacted to by all of the ISI. Signal seems to have similar impact at each building.
Second attached image are asds for the ITM and ETM STS. The live red, blue, light green are the ITM asds 10 minutes before, the rest of the unicorn vomit are the ETM ITM ground during the event. All of the extra motion is between .5 and 5 hz, and looks like generall same magnitude at all stations.
Still not sure what happened, maybe a very small local earthquake? There was no fence work going on at EY. I don't think construction on 240 would impact the whole site this way.