Ethan, Jenne, Guillermo

There is some presence of scattering arches between 20Hz-50Hz in the GW channel in the last few days.
These arches seem to appear every ~3s, so the surface from which the scattered light is being reflected is moving back and forth with a frequency of ~1/6s.

According to the Scattering Summary Pages, ETMX has some excess motion that is coincident with the scattering glitches. Here is one example: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20191211/detchar/scattering/

Also, we appreciate scattering arches in the DHARD signals at even lower frequencies, approximately at 10Hz. Here are a couple of examples:
https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20191212/1260144018-1260230418/scans/1260213392.8125/
https://ldas-jobs.ligo-wa.caltech.edu/~detchar/hveto/day/20191212/1260144018-1260230418/scans/1260224771.1875/

This investigation is somewhat similar to the one made at LLO in November 2018:
https://alog.ligo-la.caltech.edu/aLOG/index.php?callRep=41960