Krishna had noted in a log in the secret SEI logbook that the endstation BSC tilt subtracted sensor correction wasn't performing as well as the corner station sensor correction. This seems to have been due to a high pass added to the tilt subtracted seismometer path. This filter is supposed to help suppress signal from the BRS 8mhz resonance, but it seems to have been distorting the phase of the STS signal too much at 100mhz. The first attached plot is of an older (I think) high pass in red and the "problematic" high pass in blue. I've switched ETMX to the "old" high pass, second plot are the ground STS to St1 T240 tf for each endstation. Red trace is EX, blue is EY. It's subtle, but EX is doing better in the 100-200mhz band, if you squint. I'm going to leave the endstations in this configuration overnight, while people in the seismic group can come up with reasons why this is a bad idea.