Today we have continued the investigation of NE/WE and PR offsets. First a 2mm common offset on NE/WE, then PR moved by 100um, then the NE/WE common offset increased to 3mm, then the PR offset removed, and finally the NE/WE common offset removed. The interferometer unlocked during that last step.

Figure 1. In this case the PR offset reduced the B2 power only by a small amount, and increased significanly the B2 power fluctuations at low frequency (much below 1Hz). The PR offset may have reduced the B1s power by a few percent. The increase in carrier gain and DARM gain from the NE/WE common offset was clearly present again.