After August’s work, we wanted to check the ITMY compensation plate yaw setting. I did this last week using an input arm shaker injection at 12.6 Hz while sweeping the ITMY compensation plate in yaw, as I had done several times in the past (e.g. 76969, Figure 3).

The figure shows that scattering noise continues to be quite sensitive to the CP yaw on a 20 microradian scale. While re-checks did not previously suggest the need for a change after the initial setting (76969), the figure shows that this time the check suggests a new setting. The original setting, -250,  is now in a coupling peak. I suggest changing it to -325 (see figure).

The second page of the figure shows that the coupling peaks are very repeatable.