Beverly, Josh

The pitch drift value of several quad and triple optics (especially ETMX, ETMY, ITMX, ITMY) changed substantially (e.g., 200urad for ETMX) during the 6 July 2017 Montana EQ and the change persisted for most of them. A list of Summary Page links to the pitch drift for most of the optics on 6 July is given below. The attached table of images includes the actual graphs (middle column) along with the same quantity on 4 July (first column) and 25 July (3rd column) to check for persistence. Note that the actual transition is visible on 6 July, the day of the EQ. On days before and after the EQ, there is not much change within a given day but the numbers on the vertical axis indicates the qualitative value of the pitch drift.

The trends for ETMX pitch, yaw, and vertical are shown in Figs. 1-3. Pitch changes significantly but the yaw and vertical do not.. Note that the quake time is 2017-07-06 06:30:16.5 UTC, or 2 days 6:30 on the plots in Figs. 1-3, which is quite consistent with the pitch jump. 

Links to Summary Page of pitch drift on 6 July 2017 for the indicated optics:

BS: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_3A59D6_TIMESERIES-1183334418-86400.png (small change)

ETMX: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_57EB46_TIMESERIES-1183334418-86400.png (big change) 

ETMY: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_EB31EB_TIMESERIES-1183334418-86400.png (big change)

ITMX: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_12F173_TIMESERIES-1183334418-86400.png (big change)

ITMY: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_ABFA9C_TIMESERIES-1183334418-86400.png (big change)

MC1: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_ABFA9C_TIMESERIES-1183334418-86400.png (small change)

MC2:  https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_94968B_TIMESERIES-1183334418-86400.png (large change)

MC3: https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_41B596_TIMESERIES-1183334418-86400.png (large change during EQ but seems to have reverted to pre-EQ value)

PRM:  https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_F79514_TIMESERIES-1183334418-86400.png (small change)

SRM:  https://ldas-jobs.ligo-wa.caltech.edu/~detchar/summary/day/20170706/plots/H1-ALIGNED_9E8930_TIMESERIES-1183334418-86400.png (moderate change)