This is a follow up to my alog on September 1st, where I identified that IM4 pitch was changing by 60+urad during the H1 locking sequence, alog 51673, comment alog 51679, first plot.  In that plot, I also identified that IM4 Yaw was changing more than 20urad, and then changing back during the locking sequence.

Today I plotted IM4 pitch and yaw against the power control rotation stage, and the plots are attached, and what they show is that the majority of the alignment changes in IM4 happen before the rotation stage has taken it's first step in increasing power.

• IM4 pitch changes by -53urad
• IM4 yaw changes by -10urad