On July 2, 1015, Sudarshan measured the ISS first loop UGF to be about 22 kHz with a phase margin of 50 deg and only about 30 deg of phase margin near 50 kHz.

I emailed the lsc-psl@ligo.org list to see if this was observed with the other PSL installations.

Matt Heinze responded that they had recently made these measurments at LLO (see LLO alog 19412).

In summary, they also found that their ISS UGF was too low, they increased it to 50-60 kHz where they have around 30 deg. of phase margin.

Maybe we should turn our gain up too.

They also adjusted the gain of the PMC servo which we have not looked at for a long time.

Seems we should investigate both of these servos during next Tuesday's maintenance period.