Triggered by Jeff and the quite large variation of the range, I tried to see if there was any correlation with beam motion, especially as sensed by the TRANSMON QPD.

The plot attached shows the variation of the BNS range over the last week, togeher with the best fit obtained with a linear combination of the 8 TRANS QPD signals (X/Y, A/B, PIT/YAW). 

The reconstruction is not paritcularly good, but my feeling is that there might be something interesting here. It's likely that at least some part of the range variation can still be caused by a slighly different alignment state of the IFO.