Sheila asked me to look at the same trends we used to track the damage in the OFI over the 22nd and 23rd of April when it first happened. We think something like this might have happened again on Friday.

Attached you can see the optical gain, coupled cavity pole, range in Mpc, power at the anti-symmetric port, circulating power, and power reflected from the OMC all changed between April the 22nd, when the damage first started affecting the range causing it to decrease slowly.

In the next image we have the same trends from the last couple of days, there doesn't seem to be a slow degradation in range in this case, the range got worse between two locks on the 12th but nothing else seems to have degraded (unlike beforte when we observed a drop in optical gain, circulating power, output power and coupled cavity pole) before we got to the point where we couldn't relock.