We have full gradient field data from the ITMX HWS archived back to March-2016. In order to see the thermal lens, we need coincident times between low noise HWS operation and a relatively high power lock-acquisition or lock-loss of the IFO.

By mining the archived data, I can see evidence for the point source going back to 12-March-2016 [the gradient field is relative noisy]. Unfortunately, there is no archived data earlier than this time.