ACDS V10.0 - Detailed Description of I/297

ACDS V10.0 - Sun Jan 19 03:01:28 CET 2025

| # Detailed Description of I/297 : NOMAD Catalog (Zacharias+ 2005) |

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.

    I/297                     NOMAD Catalog                        (Zacharias+ 2005)
    ================================================================================
    Naval Observatory Merged Astrometric Dataset (NOMAD)
         Zacharias N., Monet D.G., Levine S.E., Urban S.E., Gaume R., Wycoff G.L.
        <San Diego AAS Meeting, January (2005)>
        =2004AAS...205.4815Z
    ================================================================================
    ADC_Keywords: Positional data ; Proper motions ; Surveys ;
                  Photometry, photographic ; Photometry, infrared

    Description:
        The  Naval Observatory Merged  Astrometric  Dataset  (NOMAD)  contains
        astrometric and photometric data for over 1 billion stars derived from
        the Hipparcos (I/239), Tycho-2 (I/259),  UCAC2 (I/289),  and USNO-B1.0
        (I/284)  catalogs for astrometry and optical photometry,  supplemented
        by 2MASS (II/246)  near-infrared photometry.  For each unique star the
        "best"   astrometric and photometric  data are chosen  from the source
        catalogs and merged into a single dataset. A sequence of priorities is
        followed  and NOMAD contains flags to identify the source catalogs and
        gives cross-reference identifications.  This first release of NOMAD is
        not a compiled catalog; that is,  if a star is identified in more than
        1 of the  above mentioned catalogs,   only 1 catalog  entry is chosen.
        Thus  the local  and global  systematic errors  of the  various source
        catalogs will be present in this version of NOMAD. All source catalogs
        astrometric  data are on the  International Celestial Reference System
        within the  limitations of the source  catalogs.

        For more information, see
          https://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/nomad

        A dedicated remote query program can be downloaded from
        http://cdsweb.u-strasbg.fr/doc/cdsclient.html

    File Summary:

           FileName      Lrecl  Records   Explanations

    ×                   80        .   This file
    × ReadMe            80        .   This file
    × out.sam          172     1000   Example of the an output of NOMAD-1

    See also:
        https://www.usno.navy.mil/USNO/astrometry/optical-IR-prod/nomad : NOMAD
                                                                  Home Page
        I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
        I/259 : The Tycho-2 Catalogue (Hog+ 2000)
        I/284 : The USNO-B1.0 Catalog (Monet+ 2003)
        I/289 : UCAC2 Catalogue (Zacharias+ 2004)
       II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)

    Byte-by-byte Description of file:  out.sam

       Bytes Format Units    Label    Explanations

       1- 12  A12   ---      NOMAD1   NOMAD-identifier (1)
      14- 24  F11.7 deg      RAdeg    Right ascension in J2000, Ep=J2000
      26- 36  F11.7 deg      DEdeg    Declination in J2000, Ep=J2000
      38- 49  A12   ---      USNO-B1  Identifier in USNO-B1 (Cat. I/284) (1)
      51- 58  I8    ---      UCAC2    ? Number in UCAC2 (Cat. I/289)
      60- 71  A12   ---      Tycho-2  ? Identification in Tycho-2 or Hipparcos (2)
          73  I1    ---    f_Tycho-2  ? [*] when distance NOMAD1/Tycho-2 > 1arcsec
      74- 75  A2    ---      YM       [YM.] Existence in YB6 or 2MASS (Cat. II/246)
          77  A1    ---      r        [BCMYTH] Source of position (3)
      79- 82  I4    mas      e_RAdeg  Mean error on RAdeg (at epRA)
      84- 87  I4    mas      e_DEdeg  Mean error on DEdeg (at epDE)
      89- 95  F7.1  mas/yr   pmRA     Proper motion in RA (*cos(Dec))
      97-104  F8.1  mas/yr   pmDE     Proper motion in Declination
     106-110  F5.1  mas/yr   e_pmRA   Mean error on pmRA
     112-116  F5.1  mas/yr   e_pmDE   Mean error on pmDE
     118-123  F6.3  mag      Bmag     ?Blue magnitude
         125  A1    ---      r_Bmag   [BCMYTHo] Origin of Bmag (3)
     127-132  F6.3  mag      Vmag     ?Visual magnitude
         134  A1    ---      r_Vmag   [BCMYTH] Origin of Vmag (3)
     136-141  F6.3  mag      Rmag     ?Red magnitude
         143  A1    ---      r_Rmag   [BCMYTHe] Origin of Rmag (3)
     145-150  F6.3  mag      Jmag     ?Infrared J magnitude (from 2MASS)
     152-157  F6.3  mag      Hmag     ?Infrared H magnitude (from 2MASS)
     159-164  F6.3  mag      Kmag     ?Infrared K magnitude (from 2MASS)
     166-170  A5    ---      Xflags   Hexadecimal flags (4)
         172  A1    ---      R        ? [R*] Recommended (R) or Problematic (*) (4)

    Note (1): NOMAD and USNO designations consist in 2 numbers
         separated by a dash of the form:  zone-number
         where zone (0000-1799) indicates a declination strip from the South
         Pole (0.1deg wide), and number is a sequential number increasing
         with right ascension.
    Note (2): The Tycho-2 number (Cat. I/259) is made of 3 numbers separated
         by 2dashes, while Hipparcos (Cat. I/239) is a sequential number.
    Note (3): Sources of the values are defined as follows:
          B = USNO-B1.0 (Monet et al., Cat. I/284)
          C = UCAC2 (Zacharias et al., Cat. I/289)
          M = 2MASS catalog of point sources (Cutri et al., Cat. II/246)
          Y = YB6 Catalog (USNO, unpublished)
          T = Tycho-2 Catalog (Hog et al., 2000, Cat. I/259)
          H = Hipparcos catalog (Table I/239/hip_main)
          o = Palomar-I blue (O) plate (for Bmag)
          e = Palomar-I red  (E) plate (for Rmag)
    Note (4): Flags are written in hexadecimal (symbols 0-f) with the
              following meaning:
      00001 = UBBIT   : Fails Blaise's test for USNO-B1.0 star
      00002 = TMBIT   : Fails Roc's test for clean 2MASS star
      00004 = YB6     : Included in YB6 catalog (Y)
      00008 = 2MASS   : Included in 2MASS catalog (M)
      00010 = TYBIT   : Astrometry comes from Tycho2 catalog (T)
      00020 = XRBIT   : Alternative correlations for same (RA,Dec)
      00040 = ITMBIT  : Alternative correlations for same 2MASS ID
      00080 = IUCBIT  : Alternative correlations for same UCAC-2 ID
      00100 = ITYBIT  : Alternative correlations for same Tycho2 ID
      00200 = OMAGBIT : Blue magnitude from O (not J) plate (o)
      00400 = EMAGBIT : Red magnitude from E (not F) plate (e)
      00800 = TMONLY  : Object found only in 2MASS catalog (M)
      01000 = HIPAST  : Ast from Hipparcos catalog (H)
      02000 = SPIKE   : USNO-B1.0 diffraction spike bit set
      04000 = TYCONF  : Tycho2 confusion flag set
      08000 = BSCONF  : Bright star has nearby faint source
      10000 = BSART   : Faint source is bright star artifact
      20000 = USEME   : Recommended astrometric standard
          * = one of SPIKE|YCONF|BSCONF|BSART|XRBIT|ITMBIT|IUCBIT|ITYBIT set
          R = USEME (recommended astrometric standard)

    History:
      * Prepared by Dave Monet.
      * 25-Sep-2024:  format migration (CDS)

    Acknowledgements:
        It is a pleasure to thank Dave Monet who forwarded a copy of the
        NOMAD catalog to CDS.
    ================================================================================
    (End)                                   Francois Ochsenbein [CDS]    09-Nov-2005