Shifter: Beverly Berger
LHO fellows: Dripta, Adrian
- LHO experienced a power glitch while observing at 03:52 UTC on 2019-07-24 and did not return to observation mode until 17:47 UTC on 2019-07-25. A summary by Jeff Kissel of the recovery effort may be found in alog 50826.
- LHO was well behaved during observing time. The behavior mentioned below appeared to be minor.
- On Monday, noise at 500 Hz - 2 kHz was seen intermittently. HVeto found a precise correlation with 4 channels: H1:PSL-BES_A_PIT_OUT_DQ, H1:IMC-L_OUT_DQ, H1:SQZ-OPO_FREQ_OUT_DQ, H1:SQZ-PSL_FF_OUT_DQ. This noise was not found during the rest of the week but has been found intermittently since 2019-03-13.
- On Wednesday before the power glitch, scattering was visible in h(t) that was likely to be due to high winds. Near the end of the first lock, the scattering in the 20-50 Hz band was picked up in hVeto by H1:ASC-SRC2_Y_OUT_DQ.
- The 48 Hz line was visible at some times on some days. So far, the culprit in the instrument is unknown although a baffle and periscope mount in HAM 3 are suspected. Studies are in progress.
- The spectra of PCALX and PCALY were compared for Friday, 19 Jul, Monday, 22 Jul, and Friday, 26 Jul. PCALX showed significant changes, PCALY seemed essentially the same.
- The same comparisons were made for the plots under DETCHAR/SPECTRA. There were (what appeared to be minor) changes but their significance is not clear.
- An earthquake at about 1h UTC on Friday was visible in SEI/BLRMS up to 1 Hz. This may mean that it was relatively nearby. An earthquake of magnitude 4.7 in Little Lake, CA at 00:42:47 UTC is likely to have been the culprit. More interesting is that glitches in h(t) related to this earthquake were picked up by hVeto in H1:LSC-MICH_IN1_DQ and H1:ASC-SRC2_Y_OUT_DQ. These same channels were also found by hVeto during a windy period on Sunday where the noise was also detected acoustically.
- Some of the described ground motion appeared to cause significant oscillation in the VCO. At those times, whistles were NOT seen.
- On Friday, a new “wandering” line appeared at about 862 Hz. It was visible only for a short time.
- Throughout the shift, the violin mode at 511 Hz was seen at the beginning of locks.
For the complete DQ shift report see https://wiki.ligo.org/DetChar/DataQuality/DQShiftLHO20190722.