The Very Large Array Low-frequency Sky Survey Redux (VLSSr)

Abstract

We present the results of a recent re-reduction of the data from the Very\nLarge Array (VLA) Low-frequency Sky Survey (VLSS). We used the VLSS catalog as\na sky model to correct the ionospheric distortions in the data and create a new\nset of sky maps and corresponding catalog at 73.8 MHz. The VLSS Redux (VLSSr)\nhas a resolution of 75 arcsec, and an average map RMS noise level of\n$\\sigma\\sim0.1$ Jy beam$^{-1}$. The clean bias is $0.66\\times\\sigma$, and the\ntheoretical largest angular size is 36 arcmin. Six previously un-imaged fields\nare included in the VLSSr, which has an unbroken sky coverage over 9.3 sr above\nan irregular southern boundary. The final catalog includes 92,964 sources. The\nVLSSr improves upon the original VLSS in a number of areas including imaging of\nlarge sources, image sensitivity, and clean bias; however the most critical\nimprovement is the replacement of an inaccurate primary beam correction which\ncaused source flux errors which vary as a function of radius to nearest\npointing center in the VLSS.\n