I used helicopter flyovers reported by operators during O3 to check the accuracy of coupling functions measured from PEM injections (combining post-O3 and pre-O3 data). For each flyover event, I produced DARM amplitude estimates for all PEM channels with significant coupling in the relevant frequency band, although I only report here channels with the highest estimated DARM amplitude.

At LHO, I examined two reported flyovers and another known flyover occuring minutes after the public superevent S190521g. The first flyover (49161) was visible in nearly all corner station and end Y accelerometers. The only DARM noise above background was at 27 Hz, at the time of the EY flyover. The highest estimates from coupling functions are all within a factor of two of the DARM level, although the EY estimates are only upper limits. The flyover near S190521g produced noise in DARM at multiples of 13 Hz (but not at the fundamental). Three of the four harmonics are  underestimated by more than a factor of two, and I don't have a good reason why, but the average of the four estimates are still within a factor of two of the actual DARM amplitude. The third flyover (49760) at 2019-06-08 17:24:00 UTC was well predicted by the septum accelerometer.

2019-05-09 21:30 UTC

2019-05-21 3:10:40 UTC

2019-06-08 17:24:00 UTC

At LLO, I examined three reported flyovers. The first two are well predicted by HAM6 accelerometers (48281, 51181). The third flyover (52081) did not produce any visible DARM noise and the only coupling estimates were upper limits, so I omit it here.

2019-09-02 17:34:00 UTC

2020-01-22 22:25:00 UTC