Shifter: Beverly Berger

LHO Fellows: Jian Liu, Kentaro Mogushi, Phillipe Nguyen, Thomas Vo

• The duty cycle averaged 70% (Thu-72.3%, Fri-72.4%, Sat-68.7%, Sun-66.3%) with the BNS range typically 55 Mpc.
• A small number of unusual, strong glitches were seen Thursday and Saturday. Following suggestions from Andy and TJ, these were seen to line up with glitching in ASC-CSOFT pitch and yaw. The former channel has been off scale since 12 June and out of spec since 7 April 2017. 
• Thirsty ravens were noticed in the PEM EY MIC channel every day between about 02:00 and 04:00 UTC and in h(t) at 94 Hz if the instrument was in lock.
• A weak (magnitude 1.9) EQ near Benton City at 07:21:15 UTC produced scattering seen in h(t) 15 seconds later. The EQ was visible only in the 0.3-10 Hz seismic bands. The response of the IFO to this "natural experiment" (thanks, Andy) could prove to be very useful.
• The violin mode excitation varied greatly with time during this period.
• Excessive glitching occurred most of the time with strong glitches at about 20'Hz, 24 Hz, and 211 Hz visible in glitchgrams. This glitching became even more pronounced on Thursday, Friday, and Saturday at somewhere between 13:00 UTC and 16:00 UTC until the lock ended. The lower frequency loud glitches were picked up by hVeto in one among SUS-ETMY_L1_NOISEMON..., SUS-ITMY_L1_WIT..., or PEM-EX_MAG_SUSRACK which seem correlated with each other.
• A number of alogs (see, e.g., alog 37799, 37874, 37846 and associated comments) in response to an alog 37775 and associated comments on the change in quad optics' pitch drift during the 6 July Montana EQ have tested a number of hypotheses to explain (or explain away) this observation. So far, no completely consistent explanation of this change has been found although a number of hypotheses have been ruled out.

See the complete results at https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20170727 for more details.