Khan, Leon, Abhik, Vibor To calculate the accuracy of the polarized primary beam, we have taken 160 subbands HBA data of 3C295, Abhik has calibrated them using BBS and SAGECAL. For now we have taken only the before­sagecal images and quantified the percentage of leakage for different point sources, which we call “observed leakage”. Then we have made a sky model from the Stokes I images using buildsky and predicted visibilities and images all Stokes using BBS and CASA respectively. Then the percentage of leakage for different sources in the simulated data were also calculated, which we call “predicted leakage”. Finally we have taken the ratio of observed and predicted leakages and plotted a histogram of the ratios. The plots are below:

Fig 1: The image is that of the polarized emission (P=|Q+iU|) in the 3C295 field; single night, 149 subbands average. The bubbles show the polarized flux as a percentage of the corresponding Stokes I flux.

Fig 2: Predicted polarized emission from an unpolarized sky model of 3C295 149 subbands avg. All these are instrumental polarization. Image metadata same as Fig 1.

Fig 3: The background image is that of simulated Stokes I. Bubbles show ratio of observed and predicted leakages.

Fig 4: A histogram of the ratios of observed and predicted leakages (shown by bubbles in Fig 3). Some kind of a Rayleigh distribution, observed leakage is usually higher than the predicted ones, which could be because of 2 reasons: noise behavior of the (maybe noise follows this distribution in P), or maybe intrinsic polarization is contributing to some of the flux in the observed images. Need to check the RM cube.