aaron.viets@LIGO.ORG - posted 13:45, Thursday 27 April 2017 - last comment - 20:27, Tuesday 13 June 2017(35840)
DCS filters for LHO data starting at 1173225472
I have produced filters for offline calibration of Hanford data starting at GPS time 1173225472. The filters can be found in the calibration SVN at this location: ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/GDSFilters/H1DCS_1173225472.npz The new filters have EPICS and calibration line parameters for computing SRC detuning parameters. See https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=35041 For suggested command line options to use when calibrating this data, see: https://wiki.ligo.org/Calibration/GDSCalibrationConfigurationsO2 The filters were produced using this Matlab script in SVN revision 4584: ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/TDfilters/H1_run_td_filters_1173225472.m The parameters files used (all in revision 4584) were: ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/params/2017-01-24/modelparams_H1_2017-01-24.conf ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/params/2017-01-24/H1_TDparams_1175954418.conf ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/CAL_EPICS/callineParams_20170411.m ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O2/H1/Scripts/CAL_EPICS/D20170411_H1_CAL_EPICS_VALUES.m Several plots are attached. The first four (png files) are spectrum comparisons between CALCS, GDS, and DCS. GDS and DCS agree to the expected level. Brief time series of the kappas and coherences are attached, for comparison with CALCS. Time domain vs. frequency domain comparison plots of the filters are also attached.
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As a sanity check, I have calibrated data from early June to test whether these filters are up to date. Spectrum comparisons between the C00 frames and these filters are shown, and some unexpected discrepancy is noted at higher frequencies. Time series of the kappas are attached as well. These agree with the summary pages (i.e., the GDS pipeline).
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It is now evident that this change did not occur during the vent, as the attached ASD ratio plot is from C01 and C00 data from May 08, 2017 at 14:00:00 UTC (GPS 1178287218), right before the vent.
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It seems this change occurred during maintenance on Tuesday, April 11. The first ASD ratio is from data right before maintenance activities, and the second is from right after. Also it is confirmed that this is not being caused by a difference in the applied kappas (so the EPICS records agree). The most likely culprit is a change in the inverse sensing filtering.
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Relevant aLOGs around April 11th -- LHO aLOG 35474, and more specifically the comment, LHO aLOG 35476 which a "small change in writeEPICs code" is mentioned. Can we compare the EPICs records committed to the repo around that time?
I traced the problem to the GDS filters installed on April 11: https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=35462 Simply regenerating those filters seems to have fixed the problem, as shown in the attached ASD ratio plot comparing C01 to the corrected GDS filter output right after maintenance on April 11. The filters were generated as described in the above aLOG, except that the SVN revision was 4781, so the exact reason for the problem is unknown. The C00 data affected by this problem starts on April 11 (GPS 1175976351), and it is still currently being affected, until we restart the GDS pipeline, no later than next Tuesday, June 20. The C01 frames are not affected by this and should be fine.
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