VLA74MHZDP - VLA 74-MHz Deep High-Resolution Survey Source Catalog
The data used to produce this survey come from observations taken on 1998 March 7 intended to map two normal galaxies at 74 MHz (NGC 4565 and NGC 4631). These two pointings were separated by 6.4 degrees, roughly the radius of the primary beam at 74 MHz, allowing them to be ideally combined to produce a single deep image roughly 17 x 10 degrees in size. The combination of VLA A-configuration resolution (25 arcsec), favorable ionospheric conditions, and pointings in directions near the NGP, where the background temperature is low, produced the deepest observation ever obtained below 100 MHz. The same algorithm that was used in the 1.4-GHz NVSS was used to identify and characterize sources in this 74-MHz survey. The source detection algorithm had a threshold such that sources must have both a peak and integrated flux density level of at least 5 times the local rms noise level. Since the rms noise level varied from 24 mJy/beam to 80 mJy mJy/beam at the chosen field edge, the absolute level of the source-detection threshold of 5-sigma likewise varied over the image.
A deep, high-resolution survey at 74 MHz. Cohen A.S., Rottgering H.J.A., Jarvis M.J., Kassim N.E., Lazio T.J.W. <Astrophys. J. Suppl. Ser., 150, 417-430 (2004)> =2004ApJS..150..417C
The radio source designation, using the '[CRJ2004]' prefix (for Cohen, Rottgering, Jarvis 2004) and the J2000 position truncated to 0.1 minutes of time in RA and 1 arcminute in Dec, viz. '[CRJ2004] JHHMM.m+DDMM', as recommended by the Dictionary Of Nomenclature of Celestial Objects.
The Right Ascension of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.01 seconds of time in the original table.
The Declination of the radio source in the selected equinox. This was given in J2000.0 equatorial coordinates to a precision of 0.1 arcseconds in the original table.
The Galactic Longitude of the radio source.
The Galactic Latitude of the radio source.
The integrated 74-MHz flux density of the radio source, in mJy (converted from the units of Jy used in the original reference table).
The radio source spectral index between 74 and 1400 MHz, with the latter measurement coming from the NVSS Catalog. 947 out of the 949 74-MHz sources have NVSS 1400-MHz matches within 60 arcsec: the 2 sources with no NVSS match ([CRJ2004] J1230.6+3247 and [CRJ2004] J1253.6+2509) have been assigned blank (null) values.