ACDS V10.0 - Detailed Description of VIII/65

ACDS V10.0 - Thu Jan 16 03:46:17 CET 2025

| # Detailed Description of VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) |

Note : this is the description file of the original catalog. This HTML page corresponds well to the original description, but some minor changes in the format may have been introduced in the FITS output files in order to allow for arithmetic operations on quantities such as coordinates and times. h:m:s and d:m:s units are normally converted into degrees, and YYYY-MM-DD into julian days.
Similarly, some slight changes may have been introduced in the units; the value given in the HTML files supersedes the value indicated in the ReadMe file for this catalogue.

    VIII/65             1.4GHz NRAO VLA Sky Survey (NVSS)      (Condon+ 1998)
    ================================================================================
    The NRAO VLA Sky Survey
         Condon J.J., Cotton W.D., Greisen E.W., Yin Q.F., Perley R.A.,
         Taylor G.B., Broderick J.J.
        <Astron. J. 115, 1693 (1998)>
        =1998AJ....115.1693C
    ================================================================================
    ADC_Keywords: Radio sources ; Radio continuum ; Surveys

    Description:
        The NRAO VLA Sky Survey (NVSS) is a radio continuum survey covering
        the sky north of -40° declination at 1.4GHz. The principal data
        products of the NVSS are a set of 2326 4x4° continuum "cubes" with
        three planes containing Stokes I, Q, and U images, plus a catalog of
        almost 2 million discrete sources stronger than a flux density of
        about 2.5mJy.

        The images all have 45 arcsecond FWHM angular resolution and nearly
        uniform sensitivity. Their rms brightness fluctuations are
        approximately 0.45mJy/beam=0.14K (Stokes I) and 0.29mJy/beam=0.09K
        (Stokes Q and U). The rms uncertainties in right ascension and
        declination vary from <= ~1arcsecond for the 400,000 sources stronger
        than 15mJy to 7arcseconds at the survey limit.

        A more detailed description is provided in the printed paper and at the
        NVSS website at           http://www.cv.nrao.edu/nvss/
        where all data products, user software, and updates were released as
        soon as they were produced and verified.

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × nvss.dat         158  1773484   The NVSS Catalog

    See also:
        VIII/59 : the FIRST Survey, version 1999Jul (White+ 1999)
        http://www.cv.nrao.edu/nvss/ : the NVSS Home Page

    Byte-by-byte Description of file:  nvss.dat

       Bytes Format Units    Label   Explanations

       1-  8  A8    ---      Field   Name of the original survey image field
                                     from which the component was derived.
      10- 16  F7.2  pix      Xpos    X position (RA direction) of the radio source
      18- 24  F7.2  pix      Ypos    Y position (Dec direction) of the radio source
      26- 39  A14   ---      NVSS    Source name (1)
      41- 42  I2    h        RAh     Right Ascension J2000 (hours) (2)
      44- 45  I2    min      RAm     Right Ascension J2000 (minutes) (2)
      47- 51  F5.2  s        RAs     [0,60] Right Ascension J2000 (seconds) (2)
          53  A1    ---      DE-     Declination J2000 (sign) (2)
      54- 55  I2    deg      DEd     Declination J2000 (degrees) (2)
      57- 58  I2    arcmin   DEm     Declination J2000 (minutes) (2)
      60- 63  F4.1  arcsec   DEs     [0,60] Declination J2000 (seconds) (2)
      65- 69  F5.2  s        e_RAs   Mean error on RA
      71- 74  F4.1  arcsec   e_DEs   Mean error on Dec
      76- 83  F8.1  mJy      S1.4    Integrated 1.4GHz flux density of radio source
      85- 91  F7.1  mJy      e_S1.4  Mean error on S1.4
          93  A1    ---   l_MajAxis  Limit flag on MajAxis
      94- 98  F5.1  arcsec  MajAxis  Fitted (deconvolved) major axis of radio source
         100  A1    ---   l_MinAxis  Limit flag on MinAxis
     101-105  F5.1  arcsec  MinAxis  Fitted (deconvolved) minor axis of radio source
     107-111  F5.1  deg      PA      [-90, 90]? Position angle of fitted major axis
     113-116  F4.1  arcsec e_MajAxis  ? Mean error on MajAxis
     118-121  F4.1  arcsec e_MinAxis  ? Mean error on MinAxis
     123-126  F4.1  deg      e_PA    ? Mean error on PA
     128-129  A2    ---   f_resFlux  [PS* ] Residual Code (3)
     131-134  I4    mJy     resFlux  ? Peak residual flux, in mJy/beam (3)
     136-141  F6.2  mJy     polFlux  ? Integrated linearly polarized flux density
     143-147  F5.1  deg      polPA  *[-90,90]? The position angle of polFlux (4)
     149-153  F5.2  mJy   e_polFlux  ? Mean error on polFlux
     155-158  F4.1  deg     e_polPA  ? Mean error on polPA

    Note (1):
        The NVSS Catalog designation is of the form
            NVSS JHHMMSS+DDMMSS
        using the standard IAU nomenclature prescription, where NVSS is the
        catalog acronym, J specifies the coordinate equinox (for J2000)
        HHMMSS are the hours, minutes, and truncated (not rounded) seconds of
        right ascension, + or - is the sign of the declination, and DDMMSS are
        the degrees, arcminutes, and truncated (not rounded) arcseconds of
        declination. Thus, the NVSS source at equinox J2000.0 coordinates of
        00h00m00.24s -20d04'49.1" is called NVSS J000000-200449. This name,
        without the leading "NVSS J" prefix, is reported in the NVSS column.
        There are four cases where a suffix "a" or "b" have been appended to
        the name to ensure the naming unicity.
    Note (2): Position of the centroid of the fitted radio source,
        for the epoch of observation (1995±2).
    Note (3): High residual values generally indicate complex sources.
        f_resFlux contains a flag indicating a residual of the fit to the
        radio source, which can be:
          P: if the peak flux density residual was high
          S: if the integrated flux density residual was high
    Note (4):
        polPA is the position angle (N through East) of the "E" vector of the
        linear polarization if the source was detected (1 sigma) in linear
        polarization.

    History:
        The file "nvss.dat" was created from the ascii edition of NVSS as file
        ftp://ftp.cv.nrao.edu/nvss/CATALOG/NVSSCatalog.text.gz  (27-Sep-2002),
        provided by the NVSS Catalog's authors.
        Many of the descriptions enclosed in this ReadMe file were prepared
        by the HEASARC team at
        http://heasarc.gsfc.nasa.gov/W3Browse/all/nvss.html
    ================================================================================
    (End)                                   Francois Ochsenbein [CDS]    24-Dec-2002