J. Betzwieser, D. Bhattacharjee, J. Kissel, R. Savage

Executive summary: More changes to calibration lines in order to commission the best answer out of the PCALXY comparison.

Based on the systems level compromises discussed on Friday last week about having the PCALX contribution to the PCALXY comparison right next to the 410.3 Hz PCALY line that's used for TDCFs (LHO:69175), I moved the PCALX comparison line from 410.2 Hz (0.1 Hz below 410.3 Hz) to 409.8 Hz (0.5 Hz below 410.3 Hz). LHO:69303. 

After looking at the results from that move to 409.8 Hz, Joe, Rick, and Dripta re-discovered that there's a notch in the DARM loop at 410.3 Hz (see LHO:48530), which is a relatively wide elliptic bandstop (whose boundaries are 409.4 and 411.2 Hz, i.e. 410.3 +/- 0.9 Hz). That means the frequency response change of IFO's response function, C / (1 + G), is changing quite rapidly between the two 410.3 and 409.8 Hz frequencies. *That* means that the traditional, easy, side-by-side PCALXY comparison of lines to arrive at a ratio of amplitudes -- which assumes that the response function ratio isn't changing between frequencies -- becomes harder, and loop model dependent.

As such, yesterday, Joe, Rick, and Dripta got together and posted the proposal outlined last night LHO:69331, to move the lines that inform the PCALXY comparison entirely away from 410.3 Hz, such that the comparison is between
     H1:CAL-PCALX_PCALOSC8_OSC_FREQ    283.91       Already present as a "Systematic Error" line, but now louder, increasing amplitude from 200 to 2000 cts.
     H1:CAL-PCALY_PCALOSC4_OSC_FREQ    284.01       New PCALY line dedicated to this test, set with an amplitude of 1430 cts 

I've implemented their proposal at of 2023-05-05 20:00 UTC.

Knock-on effects:
    - Because there's a new line on PCALY, I wanted to check whether we still have enough OFS range to drive the temporary, ER15 "thermalization" lines, driven by the CAL_AWG_LINES guardian. We do, so we're good there.
    - The new addition of 284.01 Hz PCALY *may* impact (bias) the demodulation (answer) of the 283.91 Hz PCALX systematic error line, given that that line's front-end DEMOD still uses a +/- 0.1 Hz wide SIG band pass, and 0.1 Hz corner frequency low pass, i.e. a 10 second FFT.
    - Because the systematic Error line is much louder, and has a new companion, equally loud "next door," the CW searches may be more likely to complain about sidebands and non-linearities not subtracted out.
    - Because I'm using a new PCALY oscillator, I need to double check that the GDS pipeline still safely subtracts this out in the GDS-CALIB_STRAIN_NOLINES channel.
    - This renders the DEMOD10 PCALX non-functional, since it's stuck demodulating the 409.8 Hz PCALX line that isn't there. Ideally, we'd convert PCALX DEMOD 10 to watching the new 284.01 Hz PCALY line, but that would require a front-end code change. Eventually, once we're done the 24.5 Hz PCALY thermalization line, then we can switch that PCALY DEMOD 4 over to using that. 

Things that need to change in order to accommodate this move:
    (1) Accepted new oscillator settings in h1calex and h1caley SDF systems.
    (2) Modified the pydarm_H1.ini parameter file which now is up to version marked by git hash 156230c7. Parameters cal_line_cmp_pcalx_frequency and cal_line_cmp_pcaly_frequency have changed.
    (3) Pushed new DARM_ERR / PCAL and DELTAL / PCAL EPICs records at these line frequencies with the updated parameter file, using the command
        $ pydarm export --push --epics-only --model /ligo/groups/cal/H1/ifo/pydarm_H1.ini
    (4) Accepted them in h1calcs SDF.

Rick said he's going to take care of modifying the DEMOD SIG and low pass filters for the X Y comparisons as he needs.

Here's the latest list of calibration lines:
Freq (Hz)   Actuator               Purpose                      Channel that defines Freq             Since O3
15.6        ETMX UIM (L1) SUS      \kappa_UIM excitation        H1:SUS-ETMY_L1_CAL_LINE_FREQ          Amplitude Change on Apr 2023 (LHO:68289)
16.4        ETMX PUM (L2) SUS      \kappa_PUM excitation        H1:SUS-ETMY_L2_CAL_LINE_FREQ          Amplitude Change on Apr 2023 (LHO:68289)
17.1        PCALY                  actuator kappa reference     H1:CAL-PCALY_PCALOSC1_OSC_FREQ        Amplitude Change on Apr 2023 (LHO:68289)
17.6        ETMX TST (L3) SUS      \kappa_TST excitation        H1:SUS-ETMY_L3_CAL_LINE_FREQ          Amplitude Change on Apr 2023 (LHO:68289)
33.43       PCALX                  Systematic error lines       H1:CAL-PCALX_PCALOSC4_OSC_FREQ        New since Jul 2022 (LHO:64214, LHO:66268)
53.67         |                        |                        H1:CAL-PCALX_PCALOSC5_OSC_FREQ        Frequency Change on Apr 2023 (LHO:68289)
77.73         |                        |                        H1:CAL-PCALX_PCALOSC6_OSC_FREQ        New since Jul 2022 (LHO:64214, LHO:66268)
102.13        |                        |                        H1:CAL-PCALX_PCALOSC7_OSC_FREQ           |
283.91        V                        V                        H1:CAL-PCALX_PCALOSC8_OSC_FREQ           V
284.01      PCALY                  PCALXY comparison            H1:CAL-PCALY_PCALOSC4_OSC_FREQ        TURNED ON THIS ALOG
 ----       PCALX                  PCALXY comparison            H1:CAL-PCALX_PCALOSC2_OSC_FREQ        TURNED OFF THIS ALOG
410.3       PCALY                  f_cc and kappa_C             H1:CAL-PCALY_PCALOSC2_OSC_FREQ        No Change
1083.7      PCALY                  f_cc and kappa_C monitor     H1:CAL-PCALY_PCALOSC3_OSC_FREQ        No Change
n*500+1.3   PCALX                  Systematic error lines       H1:CAL-PCALX_PCALOSC1_OSC_FREQ        No Change (n=[2,3,4,5,6,7,8])