Julianna Lewis, TonyS, RickS This morning we moved the upper (inner) Pcal beam at X-end back to center, then horiztonal by 5 mm at the entrance aperture of the Pcal Rx sensor to test the impact on the calibration of the Pcal system at X-end. This work is a continuance from the previous movement on August 8th 2023. See the following alog, Alog from August 8th, 2023

We expect that the impact on the calibration of the Xend Pcal will be given by the dot product of the Pcal and IFO displacement vectors on the ETM.

The work proceeded as follows:

1. Disabled all excitations for the Xend Pcal system.
2. Blocked the lower (outer) beam in the transmitter module.
3. Installed a target at the entrance aperture of the Rx sensor and adjusted the roll angle so that the rows of holes in the target were aligned with the vertical and horizontal directions 
4. Increased the Pcal AOM offset in the OFS servo from 3.33 to 5.0. (GPS time 1376154600)
5. Adjusted the inner beam back to its nominal location and the Rx sensor output level increased to about 0.301 W from about 0.300 W. (GPS time 1376155600) 
6. We moved the beam horizonal to the left hole on the target  Rx sensor level was 0.312 W (GPS time 1376156390)
7. We were concerned the Rx sensor output is increased by 1 percent. After waiting, the Rx sensor droped from 0.312 W to 0.309 W. (GPS time 1376158470)
8. Removed the target from the Rx sensor. Rx sensor level 0.3326 W. With OFS offset at 5.0. (GPS time 1376158650)
9. Unblocked lower (outer) beam Rx sensor with OFS offset still at 5.0, Rx sensor 0.6679 W (GPS time 1376158845)
10. Changed OFS offset back to 3.33, Rx sensor 0.4432 W (GPS 1376149180)
11. We expect that this horizontal beam movement will change the unintended rotation of the test mass. 

We will gather data for the following 7 days and observe any changes in the X/Y comparison.