Between 09/04 00:48 and 00:50UTC the TCSX CO2 laser lost lock and pushed us out of Observing(attachment1). There were two SDF diffs for TCS-ITMX_CO2_CHILLER_SERVO_GAIN and TCS-ITMX_CO2_PZT_SERVO_GAIN(attachment2), both of which resolved themselves as the laser locked back up. Currently these unlocks are happening every ~2.8ish days. Jeff and Camilla noted(72627) that the ITMX TCS laser head power has been declining over the course of the past 1.5 months, and the drops in the power output line up with every time that the TCSX laser loses lock(attachment3).
08/15 22:00UTC - TCSX Chiller Swap to spare -> ..sn813 (72220)
08/16 08:30UTC TCSX unlock
08/18 13:30UTC ''
08/23 08:42UTC ''
08/26 09:46UTC ''
08/29 08:27UTC ''
09/01 01:44UTC ''
09/04 00:48UTC ''
TJ and I noticed that since the 72220 chiller swap, the CO2 laser temperature is 0.3degC hotter, see attached. The guardian increased the set point to relock the laser when the chiller swapped but maybe this is not a good temperature. On next IFO unlock we can try adjusting the CHILLER_SET_POINT lower. I did this with the old chiller in alog 71685 but it didn't help.
While the IFO was relocking, at 22:13UTC I reduced H1:TCS-ITMX_CO2_CHILLER_SET_POINT_OFFSET 0.3deg from 21.16 to 20.86 degC. This changed the laser tempurature 0.03degC.
