User's Guide: Viewing Calibrator Data

Assuming that the folded CAL observation is saved in the file, CAL.ar, both the data and the calibrator solution that is derived from them can be viewed with commands like the following:

Plot the total intensity, integrated over all frequency-channels and sub-integrations 
psrplot -pD -jFTp CAL.ar


The solid green line should be centred on the mean of the on-pulse and the solid red line should be centred on the mean of the off-pulse. The dashed lines are spaced one standard deviation on either side of the solid line.

Plot the on-pulse Stokes parameters as a function of frequency channel 
pacv -n csu CAL.ar

Plot the single-axis calibrator solution derived from this observation as a function of frequency channel 
pacv CAL.ar


This last image indicates that channel 0 (the data are lower sideband) yields an anomalous solution. It can be removed from the plot with the -c command line option; e.g. 
pacv -c 0 CAL.ar

Finally, plot the on-pulse Stokes parameters as a function of frequency channel, after application of calibrator to itself. 
pacv -n csc -c 0 CAL.ar


The white data points represent Stokes I (total intensity); the gain scale has been calibrated such that the CAL has a total flux of unity. The red data points represent Stokes Q; differential gain and phase have been applied such that Stokes U and V (green and blue) are zero. The negative values of Stokes Q are indicative of the symmetry angle of the receptor basis, which is set to -90 degrees in this example file (as can be queried with psredit -c rcvr:sa CAL.ar). Stokes Q dips toward zero at the edges of the band, indicating instrumental depolarization most likely due to two-bit quantization effects.