[Craig, Daniel, Georgia, Cao, Gavin, Timesh]

Cal SVN root: /ligo/svncommon/CalSVN/aligocalibration/trunk

We changed the H1:LSC-SRCL1_OFFSET to 50 counts with a 15 second ramp the set the IFO to NLN_CAL_MEAS. The approximate time of the change was 2019-11-01 05:11:36 UTC (1256620314.918 GPS). The injection files used were (files run in the order given below):
PCAL Sweep:   ^/Runs/O3/H1/Measurements/2019-10-31_H1_50ctSRCLOffset_PCALY2DARMTF_LF_SS_5t1100Hz_10min.xml    (r8655)
OLG Sweep:   ^/Runs/O3/H1/Measurements/2019-10-31_H1_50ctSRCLOffset_DARM_OLGTF_LF_SS_5to1100Hz_15min.xml    (r8655)

The raw data, the raw data, the MCMC model with the measurement, the reference model with all the measurements and MCMC corner plot of this measurement is attached to this alog. Furthermore, as Jeff Kissel had done in his comment to LHO alog 52787, the combined results for O3b SRCL offsets is attached.

There is still evidence of a spring (pro-spring) when the IFO has a SRCL offset of 50 counts however, the spring is smaller than the spring observed when using an offset of 100 counts. There still is a residual that is thought to be from the L2A2L crosscoupling (see for example LHO alog 52787, 51782, 51592). Maybe there is some merit in trying an offset of 75 counts? The downside of this would be that the squeezer system would need to be re-tuned for the new offset since Nutsinee is currently tuning the squeezer to the 50 counts offset configuration (See alog by Nutsinee in the future).