Rich and I are trying to figure out what we can use the BRS for more than tilt subtraction of the ground seismometer. Today, we looked at coherence between the BRS and ISI rotational dofs and it doesn't look promising. To check this, we took the chamber to offline, so we could compare the ground rotation seen by the ISI to the motion measured by the BRS.  The first plot shows the coherence between the BRS and the ISI, and, sadly, there doesn't seem to be any in RX. Brown and pink are the coherence to the ISI's T240RX and CPSRX, light blue is the T240Y to the BRS RX.  The next plot shows what is working well, the tilt subtration from the Y ground STS. Red is the coherence between the BRS and the corrected STS signal, blue is the coherence between the BRS and the uncorrected STS signal, below .1hz the coherence pretty much disappears on the corrected signal until about 10mhz where the subtraction makes the STS signal worse, which we expect. The last attached plot shows the different spectra, calibrated into rad or m, as appropriate.  Not a whole else to add, other than the wind was moderate (~10mph) during this measurement, so we probably should expect more coherence with higher winds. Friday looks like a more "promising" forecast, with respect to winds.