VLSSR - VLA Low-Frequency Sky Survey Redux Source Catalog
In their 2012 and 2014 reference papers, the authors present the details of improvements to data processing and analysis which were used for a re-reduction of the VLSS data, which they dub the VLSS redux or VLSSr. They used the VLSS catalogue as a sky model to correct the ionospheric distortions in the data and create a new set of sky maps and corresponding catalog at 73.8 MHz. The VLSS Redux (VLSSr) has a resolution of 75", and an average map rms noise level of sigma ~ 0.1 Jy beam-1. The clean bias is 0.66 x sigma and the theoretical largest angular size is 36 arcminutes. Six previously unimaged fields are included in the VLSSr, which has an unbroken sky coverage over 9.3 steradian above an irregular southern boundary. The final catalog includes 92,965 sources (in the abstract of Lane et al. (2014) it states 92.964 sources). The VLSSr improves upon the original VLSS in a number of areas including imaging of large sources, image sensitivity, and clean bias; however the most critical improvement is the replacement of an inaccurate primary beam correction which caused source flux errors which vary as a function of radius to the nearest pointing center in the VLSS.
The Very Large Array Low-frequency Sky Survey Redux (VLSSr) Lane W.M., Cotton W.D., van Velzen S., Clarke T.E., Kassim N.E., Helmboldt J.F., Lazio T.J.W., Cohen A.S. <Mon, Not. RAS, Volume 440, 327> =2014MNRAS.440..327L VLSS redux: Software improvements applied to the Very Large Array Low-Frequency Sky Survey Lane W.M., Cotton W.D., Helmboldt J.F., Kassim N.E. <Radio Science, Volume 47, CiteID RS0K04> =2012RaSc...47.....L
A unique sequential identification number NNNNN for each source in the VLSSr Catalog in order of increasing J2000.0 Right Ascension. This parameter, essentially the row number of the entry in the original input file CATALOG.FIT, was added by the HEASARC. This parameter could be used to create a (unique) alternate name for the source using the standard Dictionary of Nomenclature of Celestial Objects style, viz., '[LCV2014] NNNNN', where the prefix stands for Lane, Cotton, van Velzen 2014.
The designation for the VLSSr source based on the schema recommended by the authors of the original VLSS catalog, but using the 'VLSSr' prefix, and the J2000.0 coordinates truncated to 0.1 minutes of time in RA and 1 arcminute in Declination.
The Right Ascension of the VLSSr source in the selected equinox. This was given in J2000.0 decimal degrees in the original table. The average error in RA is ~ 3".
The Declination of the VLSSr source in the selected equinox. This was given in J2000.0 decimal degrees in the original table. The average error in Dec is ~ 3.4".
The Galactic Longitude of the VLSSr source.
The Galactic Latitude of the VLSSr source.
The peak flux density of the VLSSr source at 74 MHz, in mJy/beam.
The rms noise level at 74 MHz, in mJy/beam.
The residual rms noise level at 74 MHz, in mJy/beam.
The measured (undeconvolved) major axis of the source, in arcseconds.
The measured (undeconvolved) minor axis of the source, in arcseconds.
The measured position angle of the source, i.e., the orientation of its major axis, in degrees, from north through east.
The name of the original survey field in which the source was found.
The X-axis (RA) pixel number of the source in the original survey image field (specified by the field_name parameter) in which the source was present.
The Y-axis (Dec) pixel number of the source in the original survey image field (specified by the field_name parameter) in which the source was present.