Tonight during the PI measurements we switched on the ETM ring heaters commonly to 2.5W. This made our arm-prc mode matching worse shown by a drop in the PRG.

During this time the ITMY HWS measured a reasonable drop in lensing, whereas ITMX did not, which has introduced a differential lensing. I'm not sure why ITMY has been so sensitive to this change. Currently we are down to about 45 and the arm power/RF18/PRG has become choppy looking, previously during large TCS changes when this has happened the choppiness has got worse and we lose lock more readily. However it looks like it might be leveling off around 45 now. Previously when dropping CO2Y power compared to CO2X I also a RF18 increase.