thomas.shaffer@LIGO.ORG - posted 14:59, Wednesday 08 January 2020 - last comment - 15:12, Wednesday 08 January 2020(54373)
Lock Loss 2250 UTC
Human caused. We dropped out of observing from a channel connection error when some background violin mode channels were changed. Surprised by this, while we were fixing the issue I allowed some other filters to be loaded, which killed the lock.
Cheryl made changes to the ITMX damping filters for a good reason, however we forgot to reduce the gain to zero before applying those filters. This resulted in an unfortunate lockloss due to a sharp (before we could react) increase in the ITMX violin mode amplitude.