J. Kissel,

I've gathered calibration measurements of the DARM loop's sensing function (which by necessity also measured the DARM open loop gain transfer function) as a sort of "last hurrah" of O3B. As far as I know, other than the Guardian and CDS upgrades, the configuration of the IFO hasn't changed since the end of O3B, i.e. ~37W PSL power, 50 ct SRCL detuning, and OMC whitening in the "1st stage only" configuration (without yet having improved the compensation).

The collection of calibration measurements (aside from the still constantly running calibration lines) since the official end of O3B is now as follows:
Sensing function:
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/Measurements/FullIFOSensingTFs/
        2020-08-05_H1_DARM_OLGTF_LF_SS_5to1100Hz_15min.xml
        2020-08-05_H1_PCALY2DARMTF_LF_SS_5t1100Hz_10min.xml

        2020-08-28_H1_DARM_OLGTF_LF_SS_5to1100Hz_15min.xml
        2020-08-28_H1_PCAL2DARMTF_LF_SS_5t1100Hz_10min.xml
        2020-08-28_H1_PCALY2DARMTF_BB_3min.xml

        2020-09-03_H1_PCALY2DARMTF_BB_3min.xml

        2020-09-18_H1_DARM_OLGTF_LF_SS_5to1100Hz_15min.xml
        2020-09-18_H1_PCAL2DARMTF_LF_SS_5t1100Hz_10min.xml
        2020-09-18_H1_PCALY2DARMTF_BB_3min.xml

Actuation function:
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/Measurements/FullIFOActuationTFs/
        2020-08-06_H1SUSETMX_L1_PCAL2DARM_5min.xml
        2020-08-06_H1SUSETMX_L1_iEXC2DARM_8min.xml
        2020-08-06_H1SUSETMX_L2_PCAL2DARM_6min.xml
        2020-08-06_H1SUSETMX_L2_iEXC2DARM_12min.xml
        2020-08-06_H1SUSETMX_L3_PCAL2DARM_6min.xml
        2020-08-06_H1SUSETMX_L3_iEXC2DARM_12min.xml

        2020-08-28_H1SUSETMX_L1_PCAL2DARM_8min.xml
        2020-08-28_H1SUSETMX_L1_iEXC2DARM_25min.xml
        2020-08-28_H1SUSETMX_L2_PCAL2DARM_6min.xml
        2020-08-28_H1SUSETMX_L2_iEXC2DARM_12min.xml
        2020-08-28_H1SUSETMX_L3_PCAL2DARM_6min.xml
        2020-08-28_H1SUSETMX_L3_iEXC2DARM_12min.xml
The high frequency roaming lines have not been on or present for this postO3, as the HIGH_FREQ_LINES guardian was never changed from its IDLE state.

This data has been taken with a "just in case" mentality, and will likely not get processed until we need them for comparison when then IFO is back up and running, after the ITM swap, and we're testing out higher input power than 37W. 

If anyone needs to use h(t) data for this postO3 period, the model parameters set 
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/params
        modelparams_H1_20200103.py
is still being used, is quite accurate, and the systematic error should be at the same level as described in G2001206, (and if we cared, we could use the above sensing function measurements to improve the uncertainty envelope on that systematic error.)

O3 CAL Team OUT -- see you in Summer 2021!