[Jenne, Joe B]

Jenne mentioned last night that the calibrated range seemed to jump last night, and was worried the line heights need to be increased.

Turns out she was correct.  We have a threshold of 0.01 on our uncertainty calculations for the front end uncertainty calculations which gate the GDS pipeline's accepting or rejecting current time dependent correction factors.

Looking at the summary pages, for the last hour or so of May 22nd and the first half of May 23rd, I can see the PUM real and imaginary components as reported by GDS (red lines) being stuck at a value for a while, then the uncertainty drops briefly, then updates, then freezes again.

Unfortunately, because UIM, PUM and TST are used to correct the kappa_C and F_CC (optical gain and cavity pole) calculations, those 2 calculations also stop updating, although they seem to be closer the raw values (grey lines) on those pages.

I've included trends of the low frequency line uncertainties, and I can clearly see the PUM line crossing the 0.01 several times in the last 10 days or so.  I also took a quick look at a quiet time spectrum versus a recent spectrum, and there may be a bump at 16.5 Hz causing a problem for the PUM line.

At a minimum I'd suggest raising the PUM line amplitude by more than a factor of 2 (trend is nearly touching 0.02, factor of two would drop it only to 0.01).  I'd probably suggest a factor of 4.  UIM also looks like it is kinda close, so I'd recommend raising that by a factor of 2.

The channels which control the suspension line heights are H1:SUS-ETMX_{L1,L2,L3}_CAL_LINE_CLKGAIN, where the usual L1=UIM, L2=PUM, L3=TST applies. 

We should consider setting up a monitor that alerts the operator when this kind of condition occurs, similar to what LLO has set up (although we've gone a step further where we automatically increase the line height in these kinds of conditions after an hour).  See Vlad's LLO alog 71177