travis.sadecki@LIGO.ORG - posted 10:56, Friday 21 August 2015 - last comment - 15:47, Sunday 23 August 2015(20744)
PCal line turned back on
Sudarshan reports that a PCal line was turned off sometime last night. He is turning it back on at 17:53.
Darkhan, Sudarshan
Pcal Lines got turned off last night during a pcal sweep measurements (LHO alog 20734 and 20732) because the optical follower servo got unlocked. We turned two lines one at 36.7 Hz and the other one at 331.9 Hz back on. We ramped it slowly to avoid any lock loss but we still saw some drop in the range. We left the higher frequency line at 1083.7 Hz off for now. We will turn this back on during the comissioning period or next lockloss opportunity.
Attached is a trend of Optical Follower Servo error signal showing when the lines got turned off. (around 2015-08-21 07:20:00 UTC)
Are we meant to be able to see the PCal lines in the normalised spectrogram of DARM? You can see them disappear and turn on again at about the times you mention, see the first plot (this is GDS strain). Also PCal End Y doesn't look so happy, see second plot. Plots were taken from the PCal part of the summary pages
Yes, Pcal line are supposed to appear in h(t).
Also, the third line at 1083.7 Hz is turned back on after the lockloss.
What's the best way for Operators to confirm whether PCal (and DARM) Cal Lines are present? (seeing Excitation on CDS Overview? looking for lines on DARM spectra? Navigating to Calibration Line medms?)
Let us know and we can put this in checklists for operators to check.
I made a DTT template which has all the calibration lines on it. May be we can arrange to display this on the screen (A screenshot is attached.). The template sits on the following location.
/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/ER8/H1/Scripts/Templates/ Calibration_line_template.xml
The other way is to head to PCAL medm screen and look at the OFSPD plot on the screen. If there is no excitation this plot should be flat.