I/131A
  ------------------------------------------------------------------------
ftp://cdsarc.u-strasbg.fr/cats/I/131A

The catalogue can be queried from:
http://cdsweb.u-strasbg.fr/viz-bin/VizieR?-source=I/131A

This standardized document follows the rules of the Standard Description for
Astronomical Catalogues. For those having to work on this catalogue using
FORTRAN programs, this ReadMe file can be transformed into a f77-compliant
program which reads the files making up this catalogue, in two version:
either a f77 program loading whole files into arrays, or a f77-program
reading each data file line by line.

 ------------------------------------------------------------------------

I/131A      SAO Star Catalog J2000     (SAO Staff 1966; USNO, ADC 1990)
================================================================================
Smithsonian Astrophysical Observatory Star Catalog
    SAO Staff
   <Smithsonian Astrophysical Observatory (1966)>
================================================================================
ADC_Keywords: Positional data ; Proper motions

Description:
    This machine-readable SAO catalog from the Astronomical Data Center is
    based on an original binary version of the Smithsonian Astrophysical
    Observatory Star Catalog (SAO, SAO Staff 1966). Subsequent
    improvements by T. A. Nagy (1979) included the addition of equatorial
    coordinates in radians and cross-identifications from the Table of
    Correspondences SAO/HD/DM/GC (Morin 1973). As a prelude to creation of
    the 1984 version of the SAO, a new version of the SAO-HD-GC-DM Cross
    Index was prepared (Roman, Warren, and Schofield 1983). The 1984
    version of the SAO contained the corrected and extended cross
    identifications, all errata published up to January 1984 and known to
    the ADC, numerous errors forwarded to the ADC by colleagues, and
    errors discovered at the ADC during the course of this work. Clayton
    A. Smith of the U. S. Naval Observatory provided J2000.0 positions and
    proper motions for the SAO stars. Published and unpublished errors
    discovered in the previous version (1984) have been corrected (up to
    May 1991). The catalog contains SAO number; the right ascension and
    declination with a B1950.0 equinox and epoch; annual proper motion and
    its standard deviation, photographic and visual magnitudes; spectral
    type; references to sources; the Durchmusterung (DM) identifier if the
    star is listed in the Bonner DM (BD), Cordoba DM (CD), or Cape
    Photographic DM (CP); component identification; The Henry Draper
    (Extension) (HD or HDE) number; and J2000 positions and proper
    motions. Multiple-star component identifications have been added to
    stars where more than one SAO entry has the same DM number. The Henry
    Draper Extension (HDE) numbers have been added for stars found in both
    volumes of the extension. Data for duplicate SAO entries (those
    referring to the same star) have been flagged. J2000 positions in
    usual units and in radians have been added.

File Summary:
  ------------------------------------------------------------------------

       FileName      Lrecl  Records   Explanations
  ------------------------------------------------------------------------

? ReadMe            80        .   This file
? sao              204   258997   The SAO J2000.0 catalogue
? sao.doc           85     1479   Complete Documentation (extracted from the
                                 CD-ROM "Selected Astronomical Catalogs",
                                 Vol. 1, NASA 1991)
  ------------------------------------------------------------------------

Byte-by-byte Description of file:  sao
  ------------------------------------------------------------------------

   Bytes Format  Units   Label    Explanations
  ------------------------------------------------------------------------

   1-  6  I6     ---     SAO      [1/258997]+ SAO Catalog number
       7  A1     ---     delFlag  [D] if star deleted (ignore all fields)
   8-  9  I2     h       RAh      Hours RA, Equinox=B1950, Epoch=1950.0
  10- 11  I2     min     RAm      Minutes RA, equinox B1950, Epoch=1950.0
  12- 17  F6.3   s       RAs      Seconds RA, equinox B1950, Epoch=1950.0
  18- 24  F7.4   s/a     pmRA     Annual proper motion in RA (FK4 system)
  25- 26  I2     mas/a   e_pmRA   Standard deviation in pmRA
      27  A1     ---    RA2mFlag  [+-] '+', add 1, or '-', substract 1,
                                    RA minute: indication that the minutes
                                    of time associated with the seconds
                                    portion RA2 must be increased or
                                    decreased by 1
  28- 33  F6.3   s       RA2s     Seconds portion of RA, original epoch,
                                    precessed to B1950
  34- 35  I2     10mas   e_RA2    Standard deviation of RA2
  36- 41  F6.1   a       EpRA2    Epoch of RA2 (RA original epoch)
      42  A1     ---     DE-      Sign Dec, equinox B1950, Epoch=1950.0
  43- 44  I2     deg     DEd      Degrees Dec, equinox B1950, Epoch=1950.0
  45- 46  I2     arcmin  DEm      Minutes Dec, equinox B1950, Epoch=1950.0
  47- 51  F5.2   arcsec  DEs      Seconds Dec, equinox B1950, Epoch=1950.0
  52- 57  F6.3  arcsec/a pmDE     ? Annual proper motion in Dec (FK4 system) (9)
  58- 59  I2     mas/a   e_pmDE   Standard deviation of Dec proper motion
      60  A1     ---    D2m_Flag  [+-] '+', add 1, or '-', substract 1:
                                    Indication that the arcminutes
                                    associated with DE2 must be increased or
                                    decreased by 1
  61- 65  F5.2   arcsec  DE2s     Seconds of Declination, original epoch,
                                    precessed to B1950
  66- 67  I2     10mas   e_DE2    Standard deviation of DE2
  68- 73  F6.1   a       EpDE2    Epoch of DE2 (Declinaation original epoch)
  74- 76  I3     10mas   e_Pos    Standard deviation of position at epoch 1950.0
  77- 80  F4.1   mag     Pmag     []?=99.9 Photographic magnitude
  81- 84  F4.1   mag     Vmag     []?=99.9 Visual magnitude
  85- 87  A3     ---     SpType   Spectral type, '+++' for composite spectra
  88- 89  I2     ---     r_Vmag   Coded source of visual magnitude (1)
  90- 91  I2     ---     r_Num    Coded source of star number and footnotes (2)
      92  I1     ---     r_Pmag   Coded source of photographic magnitude (3)
      93  I1     ---     r_pmRA   Coded source of proper motions (4)
      94  I1     ---    r_SpType  Coded source of spectral type (5)
      95  I1     ---     Rem      Coded remarks duplicity and variability (6)
      96  I1     ---     a_Vmag   Accuracy of V: 0 = 2 decimals, 1=1 decimal
      97  I1     ---     a_Pmag   Accuracy of Ptg: 0 = 2 decimals, 1=1 decimal
  98- 99  I2     ---     r_Cat    Code for source catalog (7)
 100-104  I5     ---     CatNum   Number in source catalog
 105-117  A13    ---     DM       Durchmusterung identification, as
                                    catalog 'BD', 'CD', 'CP' (A2)
                                    zone and number (A8), and
                                    component identification (A2) if there
                                        are two or more SAO stars having
                                        the same DM number
                                    supplement letter (A1) for BD
                                        (Warren and Kress, Catalogue I/71)
 118-123  A6     ---     HD       Henry Draper Catalog (HD or HDE) number (A6)
                                    (Catalogue III/135)
     124  A1     ---     m_HD     HD component and multiple code (8)
 125-129  A5     ---     GC       Boss General Catalog (GC) number
                                    (Catalogue I/113)
 130-139  D10.8  rad     RArad    Right ascension, 1950.0, in radians
 140-150  D11.8  rad     DErad    Declination, 1950.0, in radians
 151-152  I2     h       RA2000h  Hours RA, equinox, epoch J2000.0
 153-154  I2     min     RA2000m  Minutes RA, equinox, epoch J2000.0
 155-160  F6.3   s       RA2000s  Seconds RA, equinox, epoch J2000.0
 161-167  F7.4   s/a    pmRA2000  Annual proper motion FK5 system
     168  A1     ---     DE2000-  Sign Dec, equinox, epoch J2000.0
 169-170  I2     deg     DE2000d  Degrees Dec, equinox, epoch J2000.0
 171-172  I2     arcmin  DE2000m  Minutes Dec, equinox, epoch J2000.0
 173-177  F5.2   arcsec  DE2000s  Seconds Dec, equinox, epoch J2000.0
 178-183  F6.3  arcsec/a pmDE2000  ? Annual proper motion in FK5 system (9)
 184-193  D10.8  rad   RA2000rad  Right ascension, J2000.0, in radians
 194-204  D11.8  rad   DE2000rad  Declination, J2000.0, in radians
  ------------------------------------------------------------------------

Note (1): Visual Magnitude Sources:
  -------------------------------------------------------------------------
         Photo-
  Visual visual Magnitude source
  -------------------------------------------------------------------------
    0           Does not appear in source catalog
    1      21   Determined by source catalog
    2      22   Determined by source catalog or by authority in footnote
    3      23   Source cited in source catalog introduction
           24   Source unspecified
    5           Taken from "Bonner Durchmusterung"
    8           Based on Durchmusterung magnitudes and visual estimates
    9           Taken from AGK1
   10           Taken from Cordoba Zones (Resultados)
   12           Taken from CGA (Perrine 1911a, b) or Cordoba Zones
   13           Taken from Harvard publications
   14           Taken from Harvard or San Luis photometry
   15           Taken from the "Henry Draper Catalogue"
   16           Combined magnitude of component stars
   17           Arithmetic mean of maximum and minimum magnitudes of a
                  variable star
  -------------------------------------------------------------------------
   Always check the duplicity / variability code (Note 6) when using
   magnitudes. When blank, code = 0 and field = 99.9.
Note (2): Star-Number Sources and Footnotes:
  --------------------------------------------------
    Footnote
  without with  Star Number
  --------------------------------------------------
    0      16   Source catalog only
    1      17   Source catalog and BD
    2      18   Source catalog and CD
    3      19   Source catalog and CPD
    4      20   Cordoba B (Resultados) and CD
    5      21   Cordoba A (Resultados) and CD
    6      22   AGK1 and BD
    7           GC and BD
    8      24   Cordoba B (Resultados) and CPD
    9           Cordoba A (Resultados) and CPD
  --------------------------------------------------
  When blank, the code for DM is 0 or 16, footnote is 0 through 9,
  and field is all zeros. Footnotes and star numbers are those
  appearing in the source catalogs.
Note (3): Photographic Magnitude Sources:
  ---------------------------------------------------
  Code  Source
  ---------------------------------------------------
    0   Does not appear in source catalog
    1   Determined by source catalog
    4   Taken from magnitudes of the CPD and diameters
        of the  Cape Astrographic Catalogue
    8   Source cited in source catalog introduction
    9   Columbia Contributions Numbers 30 and 31
        (Schilt and Hill 1937, 1938)
  ---------------------------------------------------
  When blank, code is 0 and field is all zeros.
Note (4): Proper-Motion Sources:
  ---------------------------------------------------------
  Code  Source
  ---------------------------------------------------------
    1   Determined by source catalog
    3   Determined by comparison of catalog and Greenwich AC
    5   Determined by comparison of catalog and AGK1
    6   Determined by comparison of catalog and Greenwich AC
        on the basis of the smallest difference in positions
        (see page xiii of source reference)
    8   Determined by comparison of catalog and AGK1 on the
        basis of the smallest difference in positions
        (see page xiii of source reference)
  ---------------------------------------------------------
Note (5): Spectral-Type Sources:
  ----------------------------------------------------------
  Code  Source
  ----------------------------------------------------------
    0   Taken from the Henry Draper Catalogue or no
        spectrum in source catalog
    1   Taken from the HD with M stars reclassified by Miss Cannon
    2   Classified by G. G. Cillie
    3   Classified by Goedicke
    4   Classified by D. Hoffleit
    5   Classified by M. W. Mayall
    6   Classified at Leander McCormick Observatory
    7   Classified by Nassau and Seyfert
  ----------------------------------------------------------
  If the spectrum is composite, "+++" is stored in the field
  and the code is 0.
Note (6):  Miscellaneous Coded Remarks for Duplicity and Variability:
  -----------------------------------------------------
  Code  Meaning
  -----------------------------------------------------
    0   No additional information
    1   Double star - see source catalog for source
    2   Double star in Aitken's Double Star Catalogue
        (Aitken 1932)
    3   Double star in Burnham's Double Star Catalogue
        (Burnham 1906)
    4   Variable star in visual magnitude in source catalog
    5   Variable star in photographic magnitude in source catalog
    6   Variable star in both magnitudes
    7   Both double and variable, in either visual or
        photographic magnitudes
  -----------------------------------------------------
  When blank, code is 0, no field is involved.
Note (7): References for the Source Catalogs:
  -----------------------------------------------------
         No.      Abbreviated Title
  -----------------------------------------------------
         01       AGK2, Volume 1
         02       AGK2, Volume 2
         03       AGK2, Volume 5
         04       AGK2, Volume 6
         05       AGK2, Volume 7
         06       AGK2, Volume 8
         20       Yale Transactions 11
         21       Yale Transactions 12   Part I
         22       Yale Transactions 12   Part II
         23       Yale Transactions 13   Part I
         24       Yale Transactions 13   Part II
         25       Yale Transactions 14
         26       Yale Transactions 16
         27       Yale Transactions 17
         28       Yale Transactions 18
         29       Yale Transactions 19
         30       Yale Transactions 20
         31       Yale Transactions 21
         32       Yale Transactions 22   Part I
         33       Yale Transactions 22   Part II
         34       Yale Transactions 24
         35       Yale Transactions 25
         36       Yale Transactions 26   Part I
         37       Yale Transactions 26   Part II
         38       Yale Transactions 27
         40       Cape Annals 17
         41       Cape Annals 18
         42       Cape Annals 19
         43       Cape Annals 20
         48       Cape Zone
         60       Melbourne 3
         61       Melbourne 4
         70       GC
         71       FK3
         74       FK4
  -----------------------------------------------------
Note (8):  Explanation of HD Codes:
  -------------------------------------------------------------
  Code   Meaning
  -------------------------------------------------------------
    0    Single star or primary with a companion > 0.3 mag
         (visual) fainter.
    1    Brighter component with a companion <= 0.3 mag fainter.
    2    Fainter component with a companion <= 0.3 mag brighter.
    9    The "SAO Catalog" entry refers to two consecutive
         HD numbers, the lower of which is given.
  -------------------------------------------------------------
Note (9): There are 3 blank values for the Declination proper motions for:
  SAO 208759     (pmDE=-0.180 in printed catalogue)
  SAO 208795     (pmDE=-0.042 in printed catalogue)
  SAO 212470     (pmDE=-0.072 in printed catalogue)
  ------------------------------------------------------------------------

See also:
  A more recent catalogue with better position and proper motion data,
  the so-called "PPM Catalogue" (Positions and Proper Motions)
  has been prepared at ARI (Astronomisches Rechen-Institut at Heidelberg,
  Germany); is is made of two parts:
  I/146 : PPM North Star Catalogue, 181731 stars;
  I/193 : PPM South Star Catalogue, 197179 stars.

References:
   Morin, D. 1973, Table of Correspondences SAO/HD/DM/GC, Obs. de Meudon,
      unpublished                                       =IV/12
   Nagy, T.A. 1979, Documentation for the Machine-Readable Version of the
      Smithsonian Astrophysical Observatory Catalog(ue) (EBCDIC Version),
      Systems and Applied Sciences Corporation R-SAW-7/79-34
   Roman, N.G., Warren Jr., W.H., and Schofield Jr., N.J. 1983, Documentation
      for the Machine-Readable Version of the SAO-HD-GC-DM Cross Index,
      Version 1983, NSSDC/WDC-A-R&S 83-17

Historical Notes:
 * Changes since 1984 Version: see in file "sao.doc", section 4.
   by Nancy G. Roman and Wayne H. Warren.
 * October 1991: CD-ROM "Selected Astronomical Catalogs" Vol. 1,
   directory:  /astrom/saoj2000
 * 24-Jun-1993: First standardized document at CDS
 * 25-Oct-1995: Standardized document revisited.
================================================================================
(End)                                     Francois Ochsenbein [CDS]  27-Oct-1995