Vicky, Sheila, TJ

At 17:48 UTC the green ISS railed and was turned off, which caused a drop in OPO green power and BNS range for a couple of hours, as shown in the attached screenshot. This happened because the output power of the SHG was dropping, this output power seems very sensitive to LVEA temperature and drifts for reasons we don't understand.

At around 19:37 Vicky logged in, we took squeezing out of the IFO, reset the AS42 offsets.  Vicky adjusted  H1:SQZ-OPO_ISS_DRIVEPOINT to see what the OPO trans value would be when it was around 2.5 V, she did this to get the highest OPO trans power we could while having some headroom not to rail the ISS.  This gave an OPO trans value of 55uW, so we set opo_grTrans_setpoint_uW in sqzparams to 55, reloaded the SQZ_OPO_LR guardian, requested LOCKED_CLF_DUAL_NO_ISS, then set the request back to LOCKED_CLF_DUAL.  

Since the OPO circulating power is now lower, we need a high OPO TEC setpoint to compensate for less local heating, from the sqz overview there is a opo temp ndscope template from Vicky that I used to adjust the temperature to maximize CLF_REFL6_ABS.  After this we requested FREQ_DEP_SQZ from sqz manager, and attempted to adjust the SQZ angle to improve the blrms.  I moved the sqz angle by 10 degrees and saw no change, so I set it back to the original angle and we went back to observe after Vicky accepted the new offsets in SDF.  We may need to adjust the sqz angle, but it will probably require looking at the Darm spectrum more carefully since we have low nonlinear gain and also technical noise limiting us, so the impact of being mistuned with sqz angle is smaller than normal.

This recovered some range for H1. To diagnose this issue more quickly in the future, TJ says he can add a check for the ISS status in DIAG_MAIN.  H1:SQZ-OPO_ISS_OUTPUTRAMP should be 0, if it is 1 the ISS is off and something needs to be done.