mwa_plot_calibration
This program is designed to test the effect of various options given in make_mwa_tied_array_beam on the calibration solution. The command line options for mwa_plot_calibration are a subset of those in make_mwa_tied_array_beam:
The three key options that this script is useful for testing are the -R
, -U
, and -X
options. If none of these are provided, then the default behaviour is for the relevant values to be drawn from the file RUNTIME/pq_phase_correction.txt
, where "RUNTIME" is the path set at VCSBeam compile-time. If there is an entry in pq_phase_correction.txt where the obsid falls between the "From" and "To" times (inclusive), then the values in the "Phase slope" and "Phase offset" columns are used for the -U
option, and the value in the "Reference Tile Name" column is used for the -R
option. For example, consider the following entry in pq_phase_correction.txt:
# From_(gpstime) | To_(gpstime) | Phase_slope_(rad/Hz) | Phase_offset_(rad) | Referece Tile Name | Notes 1201478418 1280275218 7.7258e-09 0.4898 LBG8 # From https://wiki.mwatelescope.org/display/MP/Polarimetry (accessed: 19 Aug 2021)
The command
mwa_plot_calibration -m 1240826896_metafits_ppds.fits -c 1240827912.metafits -C /PATH/TO/RTS/OUTPUT -N 24
would be equivalent to
mwa_plot_calibration -m 1240826896_metafits_ppds.fits -c 1240827912.metafits -C /PATH/TO/RTS/OUTPUT -N 24 -U 7.7258e-09,0.4898 -R LBG8
If there is no entry where the obsid of the target obs (in this case, 1240826896) falls between the From and To times, then the default behaviour is for the "dividing through by a reference antenna" (-R
) step to be skipped, and for no extra phase slope (-U
) to be applied. To force this behaviour (regardless of wheter there is a corresponding entry in pq_phase_correction.txt), the following command line options should be used:
mwa_plot_calibration -m 1240826896_metafits_ppds.fits -c 1240827912.metafits -C /PATH/TO/RTS/OUTPUT -N 24 -U 0,0 -R NONE
Output
The mwa_plot_calibration
program outputs the calibration solution as ASCII text with a self-describing (#-commented) header, printed to stdout. To store this output in a file for later plotting, use standard redirection, example:
mwa_plot_calibration -m 1240826896_metafits_ppds.fits -c 1240827912.metafits -C /PATH/TO/RTS/OUTPUT -N 24 -U 0,0 -R NONE > solution.txt
The outputted file can than be used with plot_calibration.py to generate plots such as those shown below.