In future charge measurements for the ETMX and ETMY will be performed on a monthly basis. Since charge was not building up very quickly (which is a good thing), hence we decided to do away with weekly measurements. This will give time and window for other critical systems to be monitored during the Tuesday maintenance. For the month of July, this is the first measurement with both ETMX and ETMY results. Past few weeks we were unable to take both the measurements due to various reasons.

The results for today's measurement is attached below. For the ETMX, the previous measurements were taken few weeks ago and since then some charge has build up on the test mass mirror, although not above the threshold (i.e.. bias voltage 50V). The long term trend for the 2nd and 3rd quadrant for the pitch mode shows a jump to 30V and 25V respectively. For the yaw mode (ETMX) there is a decline (effective bias) in the 2nd quadrant (20V)  and rise in the 3rd and 4th quadrant, the values remaining sub 40V and sub30V respectively.

The charge effective bias voltage for the ETMY looks fine and the long term trend also looks reasonable with no notable rise or decline.

All the values were restored after the measurements were complete and SDF difference removed for lock acquisition.