I have investigated the gradual increase of the BNS range from ~140 Mpc just after relocking, to ~160 Mpc a few hours after the relock by comparing the coherence between the CAL_DELTAL_EXTERNAL_DQ channel and the SUS, ASC and LSC channels to look for repeating patterns.

I have found that the LSC_SRCL_OUT_DQ channel shows a systematic decrease in coherence in the 20-50 Hz band from just after the relock to when the range has stabilized at ~160 Mpc. This is mirrored by an increase of the BNS-range count in the OAF_RANGE_BAND_3 in the hours just after relocking.

The attached plots show the coherence difference between a time at which the BNS range was at 140 Mpc, in red, and the time at which the BNS range has stabilized at 160 Mpc, in blue, for the four relocks on the 7th of July 2024. I also attached time series plots of the BLRMs for the same time period.