[Sudarshan, Jenne]
This afternoon we moved the ADS line at 22.347 Hz down to 22.147 Hz. All other ADS lines remain the same. This line was the most egregiously close to an interesting pulsar frequency.
Once the IFO relocked and the ADS alignment had converged, we opened the Yaw4 ETMX Yaw loop and changed its frequency. We made a new bandpass for the SIG filter bank, to bandpass at the new frequency. Sudarshan had calculated that we would only need to change the A2L gain by about 0.004, so we left it alone. We rephased by making I signal zero, which required increasing the phase by 5 degrees.
We then turned on the loop, and things seem stable and good. It's hard to really say, but maybe the range increased a teeny bit? We think that we have made these changes 'permanent' by editing the PREP_ASC_FOR_FULL_IFO guardian state, and accepted these values in both the safe and observe sdf files for the ASC.
During the last long lock, I had hand-selected the correct bandpass filter. However, the guardian selected the wrong bandpass for the new frequency. Since we've seen that having moved this line is okay, I just put the correct bandpass in the location that the old bandpass was, so that I didn't have to change guardian. (that place is FM6 in the demod SIG filter bank for ads yaw4). I have accepted this in the safe and observe snaps for the ASC.
Having this bandpass wrong seems to have misaligned the IFO (not surprising) enough that we had too much PRCL gain (the PRCL loop was oscillating on the high side of the phase bubble), but not enough that we had any other symptoms of poor alignment. Anyhow, next lock, having fixed the bandpass, there were no problems with the PRCL gain.