John Zweizig, Dripta, Nicolas Arnaud, Brennan Hughey

In FRS ticket 13123 it was asked whether it was okay to leave H1 in observation ready/intent while transitioning to earthquake mode.  The short answer is "yes", it appears okay to leave the IFO in observation ready mode when making this transition.

We examined glitch rate based on omicron triggers, BNS range, and other metrics during the ~minute-long period when the transition into earthquake mode was taking place for 55 of these transitions during observing time.  We compared the values to periods within a few minutes before and after the transition into earthquake mode to see whether the actual transition was having a negative impact on data quality.  The average glitch rate for SNR>6 omicron triggers does appear elevated by a factor of ~1.6 relative to surrounding times during the transition periods, but this is not nearly a substantial enough increase to warrant taking the IFO out of observing. This increased glitch rate wasn't traceable to a specific type of glitch, as the increase in glitch rate is very broad band.  Average BNS range is about 105 Mpc during the transitions into earthquake mode, which is not substantively different than the average BNS range in the minutes immediately surrounding the transition.  A direct check of the coherent WaveBurst online burst analysis shows that loud background triggers (as characterized by a significance of about one event per year of background) occur ~50% more often during the earthquake mode transition times than one would expect at a random time during the run, which is a pretty minor deviation from average background.

When assessing the data quality of candidate triggers it will be worth noting if they occur during one of these transition periods, so it will be useful for John Zweizig to continue generating the segments he produced to enable this study.  However, the impact of the transition into earthquake mode on data quality appears pretty modest.  It isn't an issue the transient searches will need to automatically veto, and it certainly isn't worth taking the IFO out of observing during the transition period.