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Displaying Calibration Tables - GPPLT

Calibration corrections can be examined with the task gpplt. This task can list and plot antenna gain, bandpass, delay and leakage terms. Most of the inputs are self-explanatory - see the help file for more information. Only a few parameters will be described here.

• The input dataset is given by the normal vis parameter.

• The device parameter specifies the PGPLOT device for the plot, whereas the log parameter gives the output logfile for the listing. Either device or log must be set.

• The options parameter determines what quantities to plot or list. Several quantities can be given, separated by commas. Possibilities are gains (i.e. the antenna gains), polarisation (the polarisation leakage terms), delays and bandpass. Additionally for dual polarisation systems, there are two quantities derived from the gains, namely xygains and xbyygain. xygains gives the X polarisation gain divided by the Y polarisation gain (or R divided by L for circular feeds). The phase of this quantity is the much reviled XY phase of the ATCA. xbyygain is the product of the X and Y polarisation gains - it is of more limited use.

  Two other options are sometimes useful. Option dots causes the plots to use small dots rather than larger blobs. This can reduce the size of plot files significantly and reduce the printing time. Option dtime causes the time axis to be plotted in decimal hours (rather than the normal hh:mm:ss). This can be useful for listings which are to be put into another package (e.g. a spreadsheet) for further analysis.

• The yaxis parameter controls whether the amplitude, phase, real or imaginary part of the gain is plotted. Several values chosen from amp, phase, real or imag can be given. When several values are given, then several plots will result from a given option for a given baseline.

• The select parameter behaves like the normal visibility selection parameter (see Section 5.5) - except that you are selecting gains rather than visibilities. Currently only a subset of the normal select commands are supported, and these are not entirely consistently handled. Antenna and time selection is supported for gains. Time selection is supported for delay and spectral correction. Antenna and frequency selection is supported for band passes.