Also I monitored the channels H1:LSC-POP_A_RF45_I_INMON and H1:LSC-POP_A_RF45_Q_INMON to check the RF photodiodes did not saturate. At -290 offset they are 16465 counts for the in phase photodiode and -3280 counts for the quadrature phase photodiode. This gives us enough headroom to avoid saturating.

J. Kissel, L. Dartez, J. Wright

Executive summary: there's been some skepticism regarding whether Craig's code that Jennie's using to process these broadband measurements is legit. It's legit. Scaled into different units, but legit.

At each SRCL offset, Louis and I grabbed short pairs of swept sine data with the calibration group's traditional DTT templates while Jennie measured the broadband transfer functions above. 

Then, using an updated version of the script from LHO:67617, which lives here:
    /ligo/gitcommon/Calibration/ifo/scripts/fullifosensingtfs/test_process_sensing_measurements_20220508.py (at git hash 182e7706)

I compared the processed results from
    - the swept-sine TFs processed with pydarm calibration infrastructure
    - the broad-band TFs processed with Jenne's code
    
We both made sure to update our pydarm parameter file to the latest, which lives in 
    /ligo/groups/cal/H1/ifo/pydarm_H1.ini
whose version is 156230c7.

Attached is the comparison -- they agree quite exquisitely, so we should have no issues trusting these results. It's just that the sensing function itself is confusing. In past Jennie's data, we had not detuned the SRC enough to differentiate between the "normal confusing garbage in the low frequency sensing function" and real detuning.

The "only" thing I had to do to Jennie's data is to divide the magnitude by a scale of (3 / 1e4). I put in that exact number without any physics but instead by eye. What's really happening in Jennie's code is that the sensing function transfer function is, as usual, the ratio of two transfer functions 
    (OMC_DCPD_SUM / PCAL) / (DARM_IN2 / DARM_EXC) = ("C" / 1+G) / (1 / 1+G)
which has units of ("milliamps" on the DCPDs) / (PCAL's DARM meters), or ("mA"/m) -- and then that's converted to ("W"/m) with the known responsitivity of the OMC DPCDs of 0.8538 A/W and a unit juggle of A/mA of 1e-3.

rather than the traditional 
    (DARM_ERR / PCAL) / (DARM_IN2 / DARM EXC) = (C / 1+G) / (1 / 1+G) 
which has units of mere (DARM_ERR counts) / (PCAL's DARM meters), or (ct/m).

As in LHO:67613, I also was watching the DC value reported in the calibrated SRCL output in order to calibrated the SRCL OFFSET into physical units, 
    SRCL OFFSET            H1:CAL-CS_SUM_SRCL_ERR_OUT16      SRCL tuning phase change (lambda_PSL = 1064 nm)
    SRCL ERR counts        "dl-" = um * 1e3 = nm             deg = (180/pi) * nm * (2*pi / 1064)
    -265                   -2.5652                           -0.86                       
    -275                   -2.6613                           -0.90
    -290                   -2.8055                           -0.95
    -310                   -3.0001                           -1.015
    -325                   -3.1460                           -1.064
    -350                   -3.3880                           -1.146
    -400                   -3.8703                           -1.31
    -450                   -4.3553                           -1.473    
which means I get the same calibration of the offset as before,
    0.009677 [nm / ct]
    0.00327  [deg / ct]

Here's a table of Jennie's data and my data per SRCL offset:
Jeff's root data dir = '/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/Measurements/FullIFOSensingTFs/'
Jennie's root data dir = '/ligo/gitcommon/noise_recorder/data/darm_noise/'

("-265 ct",
         "2023-05-08_2120UTC_H1_DARM_OLGTF_LF_SS_SRCL_m265.xml",
         "2023-05-08_2120UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m265.xml",
         "202305081410/sensing_function_tf_1367615618_May-8th-2023.txt"),
("-275 ct",
         "2023-05-08_2139UTC_H1_DARM_OLGTF_LF_SS_SRCL_m275.xml",
         "2023-05-08_2139UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m275.xml",
         "202305081432/sensing_function_tf_1367616988_May-8th-2023.txt"),  
("-290 ct",
         "2023-05-08_2157UTC_H1_DARM_OLGTF_LF_SS_SRCL_m290.xml",
         "2023-05-08_2157UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m290.xml",
         "202305081451/sensing_function_tf_1367618068_May-8th-2023.txt"), 
("-310 ct",
         "2023-05-08_2215UTC_H1_DARM_OLGTF_LF_SS_SRCL_m310.xml",
         "2023-05-08_2215UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m310.xml",
         "202305081508/sensing_function_tf_1367619127_May-8th-2023.txt"), 
("-325 ct",
         "2023-05-08_2232UTC_H1_DARM_OLGTF_LF_SS_SRCL_m325.xml",
         "2023-05-08_2232UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m325.xml",
         "202305081525/sensing_function_tf_1367620133_May-8th-2023.txt"), 
("-350 ct",
         "2023-05-08_2250UTC_H1_DARM_OLGTF_LF_SS_SRCL_m350.xml",
         "2023-05-08_2250UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m350.xml",
         "202305081542/sensing_function_tf_1367621256_May-8th-2023.txt"), 
("-400 ct",
         "2023-05-08_2307UTC_H1_DARM_OLGTF_LF_SS_SRCL_m400.xml",
         "2023-05-08_2307UTC_H1_PCAL2DARMTF_LF_SS_SRCL_m400.xml",
         "202305081601/sensing_function_tf_1367622297_May-8th-2023.txt") 
And I didn't process her -450 count offset because I broke the lock with my swept sine results.