On Tuesday I tuned the periscope in the PSL by adjusting weights and Tyler and I shut down SF2, which was responsible for the new 120 Hz HVAC peak ( https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=73378 ). Figure 1 shows the reduction of the periscope peak from tuning, and from tuning plus the fan shutdown. The fan shutdown had the greatest effect.

Figure 2 shows the disappearance of the peak from the summary pages, as well as the 3+ MPc increase in range from the fan change only.