I'm attaching a screenshot of a DTT template showing overlaid "systematic error" measurements from five different broadband excitations taken yesterday (Wed. 6/21/2023 PDT). The left column is a bode plot of CAL-DELTAL_EXTERNAL / PCALY_RX and the right is the same for GDS-CALIB_STRAIN_CLEAN / PCALY_RX. 

The trace colors and what they represent are included in the legend on the bottom left. They are also defined below.

The magenta trace was taken during a broadband PCAL excitation after the new 60W calibration was installed (on the front end and the GDS pipeline, LHO 70693). The blue, yellow, and gray traces were taken after the IFO was powered down to 60W but before the calibration was updated. As expected, they are very similar and show no discernible effects from having changed SRCL offset. We changed the SRCL offset to -165 [ct] as a quick detuning check (LHO 70677) but immediately changed it back after taking and inspecting broadband and sensing function measurements in that configuration.

The analogous measurements using GDS-CALIB_STRAIN_CLEAN (right column) show a much tighter grouping than those of CAL-DELTAL_EXTERNAL. This makes sense because the GDS pipeline applies time dependent corrections in real time (after re-timestamping). So differences between the traces on the right bode plot can be attributed to IFO differences that aren't covered by the TDCFs and other compensations in that pipeline.


"PCALY2DARM" Broadband measurements used:
The following files are located in /ligo/groups/cal/H1/measurements/PCALY2DARM_BB/.

- PCALY2DARM_BB_20230620T233459Z.xml : 75W, before RH change started, SRCL offset -265, red trace
- PCALY2DARM_BB_20230621T191103Z.xml : 60W, SRCL Offset -175, gray trace
- PCALY2DARM_BB_20230621T201220Z.xml : 60W, SRCL Offset -165, orange trace
- PCALY2DARM_BB_20230621T211010Z.xml : 60W, SRCL Offset -175, blue trace
- PCALY2DARM_BB_20230621T232125Z.xml : 60W, SRCL Offset -175, after calibration update, magenta trace

DTT template stored at /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O4/H1/Measurements/FullIFOSensingTFs/20230621_systematic_error_deltal_external_gds_calib_strain.xml


DTT reference traces:

T0: 2023-06-20 23:35:06
  Ref0: CAL-DELTAL_EXTERNAL / PCALY_RX_PD
  Ref1: GDS-CALIB_STRAIN_CLEAN / PCALY_RX_PD
T0: 2023-06-21 19:11:09
  Ref2: CAL-DELTAL_EXTERNAL / PCALY_RX_PD
  Ref3: GDS-CALIB_STRAIN_CLEAN / PCALY_RX_PD
T0: 2023-06-21 20:12:27
  Ref4: CAL-DELTAL_EXTERNAL / PCALY_RX_PD
  Ref5: GDS-CALIB_STRAIN_CLEAN / PCALY_RX_PD
T0: 2023-06-21 21:10:16
  Ref6: CAL-DELTAL_EXTERNAL / PCALY_RX_PD
  Ref7: GDS-CALIB_STRAIN_CLEAN / PCALY_RX_PD
T0: 2023-06-21 23:21:31
  Ref8: CAL-DELTAL_EXTERNAL / PCALY_RX_PD
  Ref9: GDS-CALIB_STRAIN_CLEAN / PCALY_RX_PD