Last week, during the wind fence work, the operators had been manually changing the stage of the sensor correction, BRS subtraction of the STS and asking fence work to pause while the IFO relocked. This week, I came up with a new sensor correction filter that has allowed us to work on the fence without turning sensor correction off at EY.

First plot is a time series showing the ETMY STS (top trace) and ETMY STS- BRSY (bottom) supersensor. The STS alone sees some extra noise, but it's not bad. The supersensor however sees a lot of extra signal from the BRS getting rung up. 

Second plot are the asds for these time series. All of the extra signal for this time is mostly contained below .1 hz. Signal above that is still good.

Third plot compares the nominal filter and the filter we've been running during fence work. Top plot shows the filter magnitudes in nm/nm (I'm leaving out the integrator needed to actually use the filter), the new 1/2hz filter has much more roll-off below .1hz bottom shows (1 - filter(in nm)), which is an estimate of the subtraction we should get with these filters. The nominal filter does a better job with the microseism, which was the focus when I designed it, but that is not the problem we have right now.

Fourth plot shows the timeseries output of each filter for the STS-BRSY signal from the first plot. At low frequency the CPS signal is dominated by the sensor correction. The new filters output is something like 10-20x smaller for the kicks coming from the BRS. I haven't done a real detailed comparison of the table motion yet, but we've been able to both lock and work on the fence running the new filter.

So far to run this, we've been pausing the ETMY_ST1_SC guardian and manually selecting the filter "Bad_stuff" for the Y direction on the ETMY St1 sensor correction. I've been waiting to see how long it will take to string up the rest of the fence before trying to add new guardian states to automate the transition.