J. Kissel, S. Dwyer
WP # 6448

I've installed the improved 4.7 kHz elliptic bandstop notch in FM3 of the DARM2 bank, as designed yesterday (see LHO aLOG 33546),
    User Model     Bank Name        Filter Module       Name             Design String
    H1OMC          H1:LSC-DARM2     FM3                 "not4735.25"     ellip("BandStop",4,1,80,4720,4750)gain(1.12202)
The filter file has been committed to the userapps repo, 
    /opt/rtcds/userapps/release/omc/h1/filterfiles/H1OMC.txt      (r14921)

Because this filter bank in unmonitored by SDF, yet under guardian control, we've ensured that this filter is always on by hard-coding the filter to be always on into the DOWN state of the ALS_DIFF.py guardian (line 112)
    /opt/rtcds/userapps/release/als/common/guardian/ALS_DIFF.py   (r14918)
which has been committed.

Calibration impacts:
Both the CAL-CS (which produces DELTAL_EXTERNAL) and the GDS (which produces GDS-CALIB_STRAIN) time-independent portions of the low-latency calibration pipeline are unaffected by changes to the DARM filters. However, the calculation of time-dependent correction factors (TDCFs) involves correcting for the entire DARM loop frequency dependence between calibration lines. Thus as the change to the DARM filter banks changes the DARM loop, it impacts the computation of the TDCFs, which impacts h(t). See T1500377 for details of the calculation.

That being said, the improvement in to notch reduces this impact at the calibration line frequencies to negligible. However, for completeness, traceability, reproducibility, and sanity's sake, we update the calibration model in order to account for this new filter. 

Calibration update process:
Here're the steps to ensure that the calibration has been updated to reflect the change:
- Copy the updated OMC filter file from the chans archive to the copy of the archive in the CalSVN and commit,
    ]$ cp /opt/rtcds/lho/h1/chans/filter_archive/h1omc/H1OMC_1169320184.txt /ligo/svncommon/CalSVN/aligocalibration/trunk/Common/H1CalFilterArchive/h1omc/H1OMC_1169320184.txt
- Create a new IFOparams.conf and corresponding IFOparams_YYYY-MM-DD.conf configuration files in the CalSVN,
    ]$ cd /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/params/
    ]$ svn mkdir 2017-01-24
    ]$ svn commit -m "" 2017-01-24
    ]$ cp H1params.conf 2017-01-24/     #note that the H1params.conf file in the top level of the O2/H1/params/ folder is the 2017-01-03 reference model (LHO aLOG 33004)
    ]$ cp 2017-01-03/H1params_2017-01-03.conf 2017-01-24/H1params_2017-01-24.conf
- Update IFOparams.conf file to point to the newly updated H1OMC filter file in the variable DfilterFile, and make sure the DfilterModulesInUse2 is calling out that the new filter is on in FM3, and commit to the repo.
- Make a new CAL_EPICS parameter file that points to the new reference model,
    ]$ cd /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/CAL_EPICS/
    ]$ cp callineParams_20170103.m callineParams_20170124.m
- Change par.conf.ifoDepFilename and par.conf.ifoMeasParams to point to IFOparams.conf and corresponding IFOparams_YYYY-MM-DD.conf
- Use 
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/CAL_EPICS/writeH1_CAL_EPICS.m
  to create and install new EPICs records. Be sure to update the par0 that calls the above mentioned callineParams_YYYYMMDD.m
- Accept the new records in the SDF system for both safe.snap and OBSERVE.snap, and commit
    /opt/rtcds/userapps/release/cal/h1/burtfiles/
    h1calcs_safe.snap
    h1calcs_OBSERVE.snap.

This process generates the following output for offline DCS consumption, and represent the new calibration model applicable for all lock stretches beyond 2017-01-24 20:00 UTC:
    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/params/2017-01-24/
    H1params.conf                    (r4212, lc: 4212)
    H1params_2017-01-24.conf         (r4212, lc: 4212)

    /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/CAL_EPICS/
    20170124_H1_CAL_EPICS_VALUES.txt (r4215, lc: r4215)
    D20170124_H1_CAL_EPICS_VALUES.m  (r4215, lc: r4215)
    
Because it's about time we take a new set of calibration suite measurements, I'll take a set later today and compare against this new model.