User Parameters - Bandpass CalibrationΒΆ

These parameters govern all processing used for the calibrator observation. The requested measurement set is split up by beam and scan, assuming that a given beam points at 1934-638 in the correspondingly-numbered scan. While it is possible to use the BEAM_MIN and BEAM_MAX parameters to specify a given range of beams to process for the science field, only the BEAM_MAX parameter is applied to the bandpass calibrator processing. All beams up to BEAM_MAX are split & flagged, and have their bandpass solved for. This is due to the particular requirements of cbpcalibrator.

The MS is flagged in two passes. First, a combination of selection rules (allowing flagging of channels, antennas & baselines, and autocorrelations) and (optionally) a simple flat amplitude threshold are applied. Then a sequence of Stokes-V flagging and dynamic flagging of amplitudes is done, integrating over individual spectra. Each of these steps is selectable via input parameters.

Then the bandpass table is calculated with cbpcalibrator, which requires MSs for all beams to be given. This is a parallel job, the size of which is configurable through NUM_CPUS_CBPCAL.

If a second processing job is run with a higher BEAM_MAX (and hence wanting to use beams not included in a previous bandpass solution), the bandpass table is deleted and re-made once the new beams are split and flagged.

The cbpcalibrator job can make use of a script from ACES to both plot the bandpass solutions (as a function of antenna, beam and polarisation), and to smooth the bandpass table so that outlying points are interpolated over. This produces a second table (with ”.smooth” appended to the name), which will then be applied to the science data instead of the original. There are a number of parameters that may be used to tweak the smoothing - this is intended to be an interim solution until this functionality is implemented in ASKAPsoft.

Finally, the bandpass solutions can be applied back to the 1934 datasets themselves. This will permit possible diagnostic analysis of the quality of the bandpass solution.

Variable Default Parset equivalent Description
DO_SPLIT_1934 true none Whether to split a given beam/scan from the input 1934 MS
JOB_TIME_SPLIT_1934 JOB_TIME_DEFAULT (12:00:00) none Time request for splitting the calibrator MS
DO_FLAG_1934 true none Whether to flag the splitted-out 1934 MS
JOB_TIME_FLAG_1934 JOB_TIME_DEFAULT (12:00:00) none Time request for flagging the calibrator MS
DO_FIND_BANDPASS true none Whether to fit for the bandpass using all 1934-638 MSs
JOB_TIME_FIND_BANDPASS JOB_TIME_DEFAULT (12:00:00) none Time request for finding the bandpass solution
Preparing the calibrator datasets      
MS_BASE_1934 1934_SB%s_%b.ms none Base name for the 1934 measurement sets after splitting. The wildcard %b will be replaced with the string “beamBB”, where BB is the (zero-based) beam number, and the %s will be replaced by the calibration scheduling block ID.
CHAN_RANGE_1934 “” channel (mssplit (Measurement Splitting/Averaging Utility)) Channel range for splitting (1-based!). This range also defines the internal variable NUM_CHAN_1934 (which replaces the previously-available parameter NUM_CHAN). The default is to use all available channels in the MS.
FLAG_DO_DYNAMIC_AMPLITUDE_1934 true none Whether to do the dynamic flagging, after the rule-based and simple flat-amplitude flagging is done.
FLAG_THRESHOLD_DYNAMIC_1934 4.0
amplitude_flagger.threshold
(cflag (Flagging Utility))
Dynamic threshold applied to amplitudes when flagging 1934 data [sigma]
FLAG_DYNAMIC_1934_INTEGRATE_SPECTRA true amplitude_flagger.integrateSpectra (cflag (Flagging Utility)) Whether to integrate the spectra in time and flag channels during the dynamic flagging task.
FLAG_THRESHOLD_DYNAMIC_1934_SPECTRA 4.0 amplitude_flagger.integrateSpectra.threshold (cflag (Flagging Utility)) Dynamic threshold applied to amplitudes when flagging 1934 data in integrateSpectra mode [sigma]
FLAG_DYNAMIC_1934_INTEGRATE_TIMES false amplitude_flagger.integrateTimes (cflag (Flagging Utility)) Whether to integrate across spectra and flag time samples during the dynamic flagging task.
FLAG_THRESHOLD_DYNAMIC_1934_TIMES 4.0 amplitude_flagger.integrateTimes.threshold (cflag (Flagging Utility)) Dynamic threshold applied to amplitudes when flagging 1934 data in integrateTimes mode [sigma]
FLAG_DO_STOKESV_1934 true none Whether to do Stokes-V flagging, after the rule-based and simple flat-amplitude flagging is done.
FLAG_USE_ROBUST_STATS_STOKESV_1934 true stokesv_flagger.useRobustStatistics (cflag (Flagging Utility)) Whether to use robust statistics (median and inter-quartile range) in computing the Stokes-V statistics.
FLAG_THRESHOLD_STOKESV_1934 4.0
stokesv_flagger.threshold
(cflag (Flagging Utility))
Threshold applied to amplitudes when flagging Stokes-V in 1934 data [sigma]
FLAG_STOKESV_1934_INTEGRATE_SPECTRA true stokesv_flagger.integrateSpectra (cflag (Flagging Utility)) Whether to integrate the spectra in time and flag channels during the Stokes-V flagging task.
FLAG_THRESHOLD_STOKESV_1934_SPECTRA 4.0 stokesv_flagger.integrateSpectra.threshold (cflag (Flagging Utility)) Threshold applied to amplitudes when flagging Stokes-V in 1934 data in integrateSpectra mode [sigma]
FLAG_STOKESV_1934_INTEGRATE_TIMES false stokesv_flagger.integrateTimes (cflag (Flagging Utility)) Whether to integrate across spectra and flag time samples during the Stokes-V flagging task.
FLAG_THRESHOLD_STOKESV_1934_TIMES 4.0 stokesv_flagger.integrateTimes.threshold (cflag (Flagging Utility)) Threshold applied to amplitudes when flagging Stokes-V in 1934 data in integrateTimes mode [sigma]
FLAG_DO_FLAT_AMPLITUDE_1934 false none Whether to apply a simple (“flat”) amplitude threshold to the 1934 data.
FLAG_THRESHOLD_AMPLITUDE_1934 0.2 amplitude_flagger.high (cflag (Flagging Utility)) Simple amplitude threshold applied when flagging 1934 data. If set to blank (FLAG_THRESHOLD_AMPLITUDE_1934=""), then no minimum value is applied. [value in hardware units - before calibration]
FLAG_THRESHOLD_AMPLITUDE_1934_LOW “” amplitude_flagger.low (cflag (Flagging Utility)) Lower threshold for the simple amplitude flagging. If set to blank (FLAG_THRESHOLD_AMPLITUDE_1934_LOW=""), then no minimum value is applied. [value in hardware units - before calibration]
ANTENNA_FLAG_1934 “” selection_flagger.<rule>.antenna (cflag (Flagging Utility)) Allows flagging of antennas or baselines. For example, to flag out the 1-3 baseline, set this to “ak01&&ak03” (with the quote marks). See the documentation for further details on the format.
CHANNEL_FLAG_1934 “” selection_flagger.<rule>.spw (cflag (Flagging Utility)) Allows flagging of a specified range of channels. For example, to flag out the first 100 channnels, use “0:0~16” (with the quote marks). See the docuemntation for further details on the format.
FLAG_AUTOCORRELATION_1934 false selection_flagger.<rule>.autocorr If true, then autocorrelations will be flagged.
Solving for the bandpass      
DIRECTION_1934 “[19h39m25.036, -63.42.45.63, J2000]” sources.field1.direction (cbpcalibrator) Location of 1934-638, formatted for use in cbpcalibrator.
TABLE_BANDPASS calparameters_1934_bp_SB%s.tab calibaccess.table (cbpcalibrator and ccalapply (Calibration Applicator)) Name of the CASA table used for the bandpass calibration parameters. If no leading directory is given, the table will be put in the BPCAL directory. Otherwise, the table is left where it is (this allows the user to specify a previously-created table for use with the science field). The %s will be replaced by the calibration scheduling block ID.
BANDPASS_SCALENOISE false calibrate.scalenoise (ccalapply (Calibration Applicator)) Whether the noise estimate will be scaled in accordance with the applied calibrator factor to achieve proper weighting.
NCYCLES_BANDPASS_CAL 50 ncycles (cbpcalibrator) Number of cycles used in cbpcalibrator.
NUM_CPUS_CBPCAL 216 none The number of cpus allocated to the cbpcalibrator job. The job will use all 20 cpus on each node (the memory footprint is small enough to allow this).
BANDPASS_MINUV 200 MinUV (Data Selection) Minimum UV distance [m] applied to data prior to solving for the bandpass (used to exclude the short baselines).
BANDPASS_REFANTENNA 1 refantenna (cbpcalibrator) Antenna number to be used as reference in the bandpass calibration. Ignored if negative, or if provided as a blank string (BANDPASS_REFANTENNA="").
Smoothing and plotting the bandpass      
DO_BANDPASS_SMOOTH true none Whether to produce a smoothed version of the bandpass table, which will be applied to the science data.
DO_BANDPASS_PLOT true none Whether to produce plots of the bandpass
BANDPASS_SMOOTH_AMP true none Whether to smooth the amplitudes (if false, smoothing is done on the real and imaginary values).
BANDPASS_SMOOTH_OUTLIER true none If true, only smooth/interpolate over outlier points (based on the inter-quartile range).
BANDPASS_SMOOTH_FIT 0 none The order of the polynomial (if >=0) or the window size (if <0) used in the smoothing.
BANDPASS_SMOOTH_THRESHOLD 3.0 none The threshold level used for fitting to the bandpass.
Applying the bandpass solution      
DO_APPLY_BANDPASS_1934 true none Whether to apply the bandpass solution to the 1934 datasets.
KEEP_RAW_1934_DATA true none If true, the 1934 MSs will be copied prior to having the bandpass solution applied. This means you will have copies of both the raw and calibrated datasets.

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