Sheila, Terra

Tonight we saw a new PI mode ring up due to the recent increase of ITMY ring heater power: MODE 9, 14982 Hz. Damping was successful. 

Increasing ring heater power shifts the optical beat note peak (between TEM_0,0 and TEM_0,3) down in frequency, increasing the frequency overlap with the 15000 Hz and 15070 Hz mechanical mode groups (while decreasing the overlap with the 15500 Hz mode group). MODE 9 rang up at 35 W about 3 hours into a 50 W then 35 W lock. It damped with no phase and -1000 damping gain. 

I've added active damping for MODE 9 to the SUS_PI guardian.