Astronomy & Astrophysics

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$\begin{figure} \par\includegraphics[width=7cm,clip]{9284F1a.eps}\includegraphics[width=7cm,clip]{9284F1b.eps}\end{figure}$ Figure 1: The image in the left panel shows a typical (first) diagonal term for the VLA at 1.4 GHz $\left({\ensuremath{\mathsf{J^{R}_{\it i}}} }{\ensuremath{\mathsf{J^{R^{\textstyle *}}_{\it j}}} }\right)$ of the Sky Mueller matrix. The pattern is off-center due to the off-axis location of the feeds. The image in the right panel shows the difference between the first and second diagonal term $\left({\ensuremath{\mathsf{J^{R}_{\it i}}} }{\ensuremath{\mathsf{J^{R^{\textsty... ...f{J^{R}_{\it i}}} }{\ensuremath{\mathsf{J^{L^{\textstyle *}}_{\it j}}} }\right)$ . ${\ensuremath{\mathsf{J^{Sky}_{}}} }$ was evaluated at ${\rm PA} = 0$ and normalized by the peak of one of the diagonal terms (the peak values of both diagonal terms are the same).
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{9284F2a.eps}\includegraphics[width=7cm,clip]{9284F2b.eps}\end{figure}$ Figure 2: The off-diagonal terms of the Sky Mueller matrix for VLA antennas at 1.4 GHz. The image in the left panel is of first order in the antenna leakage ( ${\ensuremath{\mathsf{J^{R}_{\it i}}} }{\ensuremath{\mathsf{J^{RL^{\textstyle *}}_{\it j}}} }$ ). The image in the right panel is the second order term in antenna leakage ( ${\ensuremath{\mathsf{J^{RL}_{\it i}}} }{\ensuremath{\mathsf{J^{RL^{\textstyle *}}_{\it j}}} }$ ). ${\ensuremath{\mathsf{J^{Sky}_{}}} }$ was evaluated at ${\rm PA} = 0$ and normalized by the peak of one of the diagonal terms (the peak values of both diagonal terms are the same).
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In the text

$\begin{figure*} \par\includegraphics[width=7cm,clip]{9284F3a.eps}\includegraphics[width=7cm,clip]{9284F3b.eps}\end{figure*}$ Figure 3: The off-diagonal term of ${\ensuremath{\mathsf{J^{Sky^\dag}_{\it i}}} }{\ensuremath{\mathsf{J^{Sky}_{\it i}}} }$ . Images in the left and right panels show the real and imaginary parts respectively. The overlayed contours correspond to $\max \left( {\ensuremath{\mathsf{J^{Sky}_{\it i}}} }[0] \right) \times [0,0.1,0.15,0.18,0.2,0.4,0.6,0.8,0.9]$ . The absolute maximum value inside the first null is $\sim$ 0.2.
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In the text

$\begin{figure} \par\vbox{ \hskip 0.3cm \hbox{ \includegraphics[width=7.8cm,clip]... ...lip]{9284F4c.eps}\includegraphics[width=7.8cm,clip]{9284F4d.eps} }} \end{figure}$ Figure 4: The top row shows the Stokes-I images and the bottom row shows the Stokes-V images. The images on the left were made without squint and pointing correction while those on the right had both corrections applied. The deconvolution errors seen around the strongest sources are due to the antenna pointing errors and time varying direction dependent gain due to the rotation of azimuthally asymmetric antenna power patterns. These images were made using a linear transfer function with the gray scales in the range - $20~\mu$ Jy/beam (black) and + $40~\mu$ Jy/beam (white). The rms noise in the off-source regions of the images in the left and the right panels is $10~\mu$ Jy/beam and $1~\mu$ Jy/beam respectively.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{9284F5a.eps}\includegraphics[width=7.6cm,clip]{9284F5b.eps}\end{figure}$ Figure 5: The Stokes-I images at 1.4 GHz with VLA C-array observation. The left panel shows the deconvolved image without corrections of the antenna power pattern variations as a function of parallactic angle. The right panel shows the result from the algorithm described in this paper. The two dominant sources, on either side of the pointing center have flux densities of $\sim$ 854 mJy/beam and $\sim$ 145 mJy/beam and the rms noise is 0.15 mJy/beam. A linear transfer function with a range $\pm$ 1.5 mJy/beam was used to make these images.
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In the text

$\begin{figure} \par\includegraphics[width=7.6cm,clip]{9284F6a.eps}\includegraphics[width=7.6cm,clip]{9284F6b.eps}\end{figure}$ Figure 6: The Stokes-V images for a 1.4 GHz VLA C-array data. The left and right panels show the images without and with PB-corrections. A linear transform with a range $\pm 1.5$ mJy/beam was used to make these images. Errors due to the polarization squint are greater than thermal noise in the left image. The rms in the right-hand-side image is $\sim 0.15$ mJy/beam. The negative and positive peaks in this image are $\pm$ 0.5 mJy/beam.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{9284F7.eps}\end{figure}$ Figure 7: Model for the VLA 1.4 GHz antenna at Parallactic Angle $\sim$ $80^\circ$ . The Stokes-V pattern ( [PB_RR-PB_LL]/2) is shown in colour/gray scale with the contours of the Stokes-I power pattern superimposed. Dark regions in the gray scale image represent negative values due to the polarization squint of VLA antenna.
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In the text

$\begin{figure} \par\includegraphics[width=8cm,clip]{9284F8.eps}\end{figure}$ Figure 8: Difference between an instantaneous Stokes-I PB and an azimuthally averaged PB ( $\overline {PB}$ ). The colour/gray scale image is $\Delta PB = PB(\psi _\circ )-\overline {PB}$ while the contours are for the $\overline {PB}$ .
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In the text

$\begin{figure} \par\includegraphics[width=80mm,clip]{9284F9.eps}\end{figure}$ Figure 9: Azimuthal cut through $\Delta PB$ shown in Fig. 8 at points where the value of the $\overline {PB}$ is at 50%, 10% and 1% of its peak value.
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In the text

$\begin{figure} \par\includegraphics[width=7cm,clip]{9284F7.eps}\end{figure}$	Figure 7: Model for the VLA 1.4 GHz antenna at Parallactic Angle $\sim$ $80^\circ$ . The Stokes-V pattern ( [PB_RR-PB_LL]/2) is shown in colour/gray scale with the contours of the Stokes-I power pattern superimposed. Dark regions in the gray scale image represent negative values due to the polarization squint of VLA antenna.
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$\begin{figure} \par\includegraphics[width=8cm,clip]{9284F8.eps}\end{figure}$	Figure 8: Difference between an instantaneous Stokes-I PB and an azimuthally averaged PB ( $\overline {PB}$ ). The colour/gray scale image is $\Delta PB = PB(\psi _\circ )-\overline {PB}$ while the contours are for the $\overline {PB}$ .
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$\begin{figure} \par\includegraphics[width=80mm,clip]{9284F9.eps}\end{figure}$	Figure 9: Azimuthal cut through $\Delta PB$ shown in Fig. 8 at points where the value of the $\overline {PB}$ is at 50%, 10% and 1% of its peak value.
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