J. Kissel

Having worked with Bubba and the Apollo Crew, we've finally settled on a stable VEA temperature that's roughly where we were before (EY dead on, EX about 0.5 [deg C] / 1 [deg F] colder). However, with the upgrade, we now see a diurnal oscillation in temperature at the 0.25 (EY) 0.5 [deg C] (EX) (0.5 / 1 [deg F], respectively) level. While there are spikes 0.1 [deg C] every ~24 hours that coincide with the peaks of the oscillation, every other temperature sensor around the VEAs report some sort of temperature oscillation that fluctuates more than this.

I attach 20 day trends for each end station, 3 types for each:
(1) Showing the FMCS temperature sensor against the most calibrated / precise sensors in and around the VEA (with the PCAL receiver module being most representative)
    Here, we see that the VEAs (FMCS, PCAL) were stable compared the exterior electronics rooms (EBAY) prior to the upgrade (16 days ago for EY, 9 days ago for EX). Now it appears that the VEA is in-sync (or delayed/anti-corellated) with the EBAYs.
(2) Showing the PCAL receiver module temperature against the vertical position of the three suspensions in the end-stations.
    Just in case you needed proof that changes in temperature are real, and larger than before the upgrade.
(3) Showing all temperature sensors in the VEA.
    More proof that even the worst, uncalibrated temperature sensors have seen the fluctuations over the past 20 days.

We haven't yet recovered the IFO fully, so it's difficult to say yet how our alignment (and other things) are really impacting the duty cycle of the IFO, but we should continue to keep an eye on this. These temperature oscillations are definitely slower than the bandwidth of the ASC loops so we should be able to control for such fluctuation -- T1100595 suggest we have about 500 [urad] of range -- but it's a question of whether we'll need to do initial alignment more often between lock stretches. 

Plus there's always a risk of temperature impacting electronics in some terrible unknown way, but given that the EBAY electronics have been oscillating in temperature since before the upgrade, it may not be any worse than before.