Before injections, I adjusted H1:SUS=SRM_M1_OPTICALIGN_P_OFFSET to minimize the 280 Hz jitter peak. I chose this offset because, when I looked back at 8 recent good locks, the jitter peak height was most sensitive to adjustments of this offset. I did this between about 2:10 and 2:30 UTC. The sharp jitter peak / background ratio was indeed very sensitive. The peaks were at a minimum around -680. Then I got in about an hour of injections. The first attachment shows the manipulations and a band pass around the 280 Hz peak and the second shows the basis for using this channel: the results of alignment offset manipulations since Sept. 23 on this band.