ACDS V10.0 - Detailed Description of VIII/16

ACDS V10.0 - Sun Jan 19 03:16:39 CET 2025

| # Detailed Description of VIII/16 : Molonglo Reference Catalogue of Radio Sources (Large+ 1991) |

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/16     Molonglo Reference Catalogue of Radio Sources (Large+ 1991)
    ================================================================================
    Molonglo Reference Catalogue of Radio Sources
        Large M.I., Cram L.E., and Burgess A.M.
       <The Observatory, 111, 72 (1991)>
       =1991Obs...111...72L
    ================================================================================
    ADC_Keywords: Radio sources

    Description:
        "408-MHz survey observations made with the Molonglo Radio Telescope
        have been used to prepare a catalogue of 12 141 discrete sources of
        listed flux density >= 0.7 Jy. The survey covers 7.85 sr of the sky
        defined by +18.5 (deg) >= dec(1950) >= -85.0 (deg), mod(b) >= 3 (deg).
        A few sources beyond the declination limits are also included. The
        catalogue comprises celestial coordinates with standard error
        typically lying between 3 and 10 arcsec and 408-MHz flux densities
        with standard error typically lying between 4 and 10 per cent.
        Galactic coordinates, notes on source morphology and cross-references
        to the Parkes Catalogues are included. The overall source density is
        1500/sr, corresponding to 0.001 per beam area. There are 7347 sources
        of listed flux density >= 1.00 Jy, at which level the catalogue is
        substantially complete. The reliability is believed to be better than
        99.9 per cent." The MRC was re-issued in 1990 with the original B1950
        coordinates supplemented by J2000 values, and an additional
        cross-reference flag `J' added to denote (extended) sources imaged at
        843-MHz by P.A. Jones. No other alterations were made to the original
        release. The MRC is now available on 5.25 inch, 1.2 Mbyte MS-DOS (IBM)
        floppy disk (0.5 inch magnetic tape is also available, but is not the
        preferred medium). In the floppy disk format, simple software is
        provided to facilitate use of the catalogue on a PC computer.

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × mrcj2000.dat      87    12141   Catalog Data
    × mrc.for           75      724   F77 code to read catalog by L. Cram (1990)
    × mrc.exe           80      693   MS-DOS executable from mrc.for

    Byte-by-byte Description of file:  mrcj2000.dat

       Bytes Format  Units   Label    Explanations

       1-  9  A9     ---     MRC     *Recommended IAU name of the source based on
                                      B1950 equinox.
      11- 12  I2     h       RAh      Right ascension (hours) in B1950 equinox
      14- 15  I2     min     RAm      RA (minutes) in B1950 equinox
      17- 20  F4.1   s       RAs      RA (sec) in B1950 equinox
          22  A1     ---     DE-      Declination sign
      23- 24  I2     deg     DEd      DEC in degrees in B1950 equinox
      26- 27  I2     arcmin  DEm      DEC in arcminutes in B1950 equinox
      29- 30  I2     arcsec  DEs      DEC in arcseconds in B1950 equinox
      32- 33  I2     h       RA2000h  Right ascension (hours) in J2000 equinox
                                       (Converted from B1950 using the STARLINK
                                        program COCO)
      35- 36  I2     min     RA2000m  RA (minutes) in J2000 equinox
      38- 41  F4.1   s       RA2000s  RA (seconds) in J2000 equinox
          43  A1     ---     DE2000-  Declination sign
      44- 45  I2     deg     DE2000d  DEC in J2000 equinox
      47- 48  I2     arcmin  DE2000m  DEC in J2000 equinox
      50- 51  I2     arcsec  DE2000s  DEC in J2000 equinox
      52- 54  F3.1   s     e_RA2000s  Standard error in RA (in seconds of time)
          55  A1     ---     n_RAs    [*] scattering flag (1)
      56- 57  I2     arcsec e_DE2000s  Standard error in Dec (in seconds of arc)
          58  A1     ---     n_DEs    [*] scattering flag (1)
      59- 65  F7.2   Jy      S408     Flux density
      66- 69  F4.2   Jy      e_S408   Standard error
          70  A1     ---     n_S408   [*] scattering flag (1)
      71- 73  A3     ---     Mflag   *[ AECMN] *Morphology flags
      74- 76  A3     ---     Cflag   *[ CJMPRST] Cross-reference flags.
      77- 81  F5.1   deg     GLON     [0,360] Galactic longitude
      82- 87  F6.1   deg     GLAT     Galactic latitude

    Note (1): A `*' indicates that the values obtained from two or more
              independent transits are scattered more than expected.
    Note on MRC:
        The first four characters are the hours and minutes of right
        ascension, and the last four the signed declination in tenths of a
        degree (unrounded). Column 9 contains the letters A, B, etc. denoting
        sources having the same eight-character IAU designation but decreasing
        flux density.
    Note on Mflag: the Morphology flags are:
      blank - no clear evidence of departure from point
      A     - Source with small-scale structure
      E     - Extended source
      C     - Complex extended source
      M     - Multiple sources (within 8 arcmin of another)
      N     - Weak neighbouring sources
    Note on Cflag:
      J  -  See Jones (1989, PhD, Sydney; published =1992ApJS...80..137J)
            the 'J' is always in byte 74
      P  -  Source lies within 2 arcmin of a Parkes source (catalog VIII/15)
      T  -  Discussed in the original MNRAS MRC paper (1981MNRAS.194..693L)
      S  -  See Schilizzi and McAdam (1975MmRAS..79....1S)
      M  -  See Clarke et al. (1976AuJPS..40....1C)
      C  -  See Cameron (1971MNRAS.152..439C)
      R  -  See Robertson (1973AuJPh..26..403R)
      Two flags at most are used in Cols 75-76, with P>T>S>M>C>R.

    Data structure:
      The machine-readable MRC is provided as 12141 ASCII records, each
      of fixed length 87 bytes (each followed by CR,LF). The first line is
      listed below, with `x' in positions that may be occupied by characters
      but are blank in the first record :
      ===========================================================================
      1        10        20        30        40        50
      |        |         |         |         |         |
      0000-506x 00 00 09.2 -50 41 31 00 02 42.5 -50 24 49x.3xx4xx

      60        70        80
      |         |         |
      xx1.28x.06xxxxxpx-64.9 321.4
      ===========================================================================

    FORTRAN code to read MRC:
      FORTRAN 77 source is included (mrc.for) to allow menu-driven reading of
      the MRC as provided here. The FORTRAN program is self-explanatory. It
      expects to find the MRC ASCII data file in the current directory and with
      the name MRCJ2000. An executable version of this FORTRAN code has been
      produced (using Microsoft FORTRAN Version 5, with a library which uses a
      co-processor should one be available) and may be invoked on an IBM AT or
      compatible by setting the correct current directory and typing `MRC'. The
      program will run faster if the source and data are placed on a hard disk.

    Historical Notes:
      The original MRC was published in Mon. Not. R. astr. Soc., Vol 194,
      pp 693-704 and Microfiches MN 194/1. (1981MNRAS.194..693L)
    ================================================================================
    (End)   F. Ochsenbein [CDS], C.-H. Joseph Lyu [Hughes STX/NASA]      01-Aug-1995