Figure 1 looking at the NI DAS line injection at 85Hz with in blue SR aligned (LN2) and in purple SR misaligned (LN3). The height of the line is lower in Hrec when SR is aligned, but it has the same height on B1s (OMC reflection). Something interesting is that the line is visible on B1p QD2 V but not in the H direction. It coulde mean that the NI DAS injection is modulating a HOM that has is mostly in the vertical direction, or that it creates a vertical beam jitter.

I wonder what it could mean. Is the NI DAS miscentered vertically? Or is it related in some way to the jumps which also correspond to mostly a vertical sideband beam motion?