NSSDC/WDC-A-R&S 89-08





           SMITHSONIAN ASTROPHYSICAL OBSERVATORY STAR CATALOG (SAO)

                DOCUMENTATION FOR THE MACHINE-READABLE VERSION


                                (VERSION 1990)






                    Nancy G. Roman and Wayne H. Warren Jr.






                                   June 1989
                                 November 1990






                                   ABSTRACT


   An updated, corrected and extended machine-readable version of the catalog
is described. Published and unpublished errors discovered in the previous
version have been corrected, and multiple-star and supplemental BD
identifications have been added to stars where more than one SAO entry has the
same Durchmusterung number. 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.






                  National Space Science Data Center (NSSDC)/
          World Data Center A for Rockets and Satellites (WDC-A-R&S)
                 National Aeronautics and Space Administration
                          Goddard Space Flight Center
                          Greenbelt, Maryland  20771


                               TABLE OF CONTENTS



Section 1 - Introduction and Procedure . . . . . . . . . . . .      1-1
Section 2 - File Contents  . . . . . . . . . . . . . . . . . .      2-1
Section 3 - File Characteristics . . . . . . . . . . . . . . .      3-1
Section 4 - Remarks, Acknowledgments and References  . . . . .      4-1
Section A - Addendum for 1990 Version  . . . . . . . . . . . .       A


                         LIST OF TABLES

Table

  1  File Contents . . . . . . . . . . . . . . . . . . . . . .      2- 1
  2  Explanation of HD Codes . . . . . . . . . . . . . . . . .      2- 5
  3  Visual Magnitude Sources  . . . . . . . . . . . . . . . .      2- 6
  4  Star-Number Sources and Footnotes . . . . . . . . . . . .      2- 7
  5  Photographic Magnitude Sources  . . . . . . . . . . . . .      2- 7
  6  Proper-Motion Sources . . . . . . . . . . . . . . . . . .      2- 8
  7  Spectral-Type Sources . . . . . . . . . . . . . . . . . .      2- 8
  8  Miscellaneous Coded Remarks for Duplicity and Variability      2- 9
  9  References for the Source Catalogs  . . . . . . . . . . .      2-10
 10  File Characteristics  . . . . . . . . . . . . . . . . . .      3- 1
 11  References for Changes to the SAO Catalog, Version 1984 .      4- 1
 12  Explanatory Notes to Individual Changes . . . . . . . . .      4- 2
 13  Changes to the 1984 Version . . . . . . . . . . . . . . .      4- 3
 14  Sources for Changes Since 1984 Version  . . . . . . . . .      4- 6
 15  Changes to the 1990 Version   . . . . . . . . . . . . . .      4- 7
 16  Sources for 1990 Changes  . . . . . . . . . . . . . . . .      4- 8























                                      ii
                    SECTION 1 - INTRODUCTION AND PROCEDURE

INTRODUCTION

A character-coded machine-readable version of the "Smithsonian Astrophysical
Observatory Star Catalog" (SAO, SAO Staff 1966) was prepared by T. A. Nagy
(1979) from a packed binary tape obtained from the Smithsonian Astrophysical
Observatory.  In addition to certain format modifications, equatorial
coordinates in radians and cross identifications from the Table of
Correspondences SAO/HD/DM/GC (Morin 1973) were added to the converted version;
however, the known errata lists were not incorporated at that time.  This
version of the catalog served as a starting point for the version described
here.  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), since most of the changes and extensions for the SAO involve data
presently in the Cross Index.  The original SAO did not use lower case letters,
making some spectral types seem strange.  All capital letters that really
should have been lower case in the spectral types have been changed.  These
changes, which are numerous, are not listed in Table 1.

The 1984 version of the SAO contains the corrected and extended cross
identifications, all errata published up to January 1984 and known to us,
numerous errors forwarded to us by colleagues, and errors discovered at the
Astronomical Data Center during the course of this work.  Recently, Clayton A.
Smith of the U.S.  Naval Observatory, volunteered to provide J2000.0 positions
and proper motions for the SAO stars.  These data have been added to the end of
each record, the positions in both sexigessimal and radian form.  Additional
errors of which we are aware (as of May 1991) have been corrected.

This document describes the current version of the machine-readable SAO
Catalog.  It outlines the procedures used to correct and extend the previous
versions and is intended to enable users to read and process the data without
problems and guesswork.  The following section describes the analysis and
methods used to cross identify the stars and to add component identifications
for stars where more than one SAO record has the same Durchmusterung (DM)
identification.  Section 2 provides detailed descriptions of the catalog format
and codes used in the data records, while Section 3 contains information on the
characteristics of the magnetic tape file.  Miscellaneous remarks and sources
for the corrections incorporated into each version and in this version are
given in Section 4, which also contains bibliographical references.  A sample
listing of data records exactly as they are recorded in the machine-readable
form comprises Section 5. A copy of this document should accompany any
machine-readable version of the SAO Catalog, originating from any one of the
International Network of Astronomical Data Centers.

PROCEDURE

The assignment of components to SAO stars for which more than one entry has the
same DM number was done when preparing the 1983 SAO-HD-GC-DM Cross Index.
That procedure is described in Roman et al. (1983). A somewhat less detailed
description is given here for completeness.

Components were assigned according to the Index Catalogue of Visual Double Stars

                                     1 - 1

(IDS, Jeffers et al. 1963; Worley 1980); for stars not in the IDS, components
were labeled according to visual magnitude.  Supplemental (footnoted) BD stars
(Warren and Kress 1980) were identified and entered with lower case letters.
Corrections and additions to cross-identification data were made as necessary.
Some duplicate DM numbers actually referred to the same star for which SAO data
had been obtained from different source catalogs.  In these cases, one record
has been marked "D" in byte 7, normally the one whose position was judged to be
of lower accuracy.  However, all data have been retained so that a different
choice may be made by the user.  Many stars occur in two DM catalogs (CD, CPD)
in the southern hemisphere.  The SAO gives numbers from different catalogs for
the components of some double stars; hence, although there are no duplicate DM
numbers, component confusion can occur.  Although a search for such systems was
not exhaustive, the catalog was searched for adjacent entries with declinations
within 3 arcmin of each other.  Most of these entries proved to be double stars
and were appended with letter designations as if their DM numbers had been the
same.  These DM numbers were not changed.

An important subset of rather bright stars in the published SAO Catalog has no
DM numbers given. (Most of the stars in this subset were identified as FK3
double stars which were omitted from the FK4.) Many of these had been identified
by W. L. Stein, who supplied probable DM numbers. The positions for these stars
were compared manually with their positions in the various DM catalogs and many
additional identifications were made.

The Astronomical Data Center (ADC) has recently completed the preparation of
machine-readable versions of the three DM catalogs: the BD, the CD, and the CPD.
Using these versions, Mr. Barry Rappaport compared the positions of the stars in
the Smithsonian Astrophysical Observatory Star Catalog (SAO) with the positions
of the DM stars whose number had been assigned to each entry. A very lengthy
list of possible assignment errors resulted. Each of these has been checked and
the assignment corrected in those cases in which correction appeared desirable.
In many cases, the assignment in the printed SAO is probably incorrect, but the
evidence was not strong enough to warrant a change. As the Henry Draper
Catalogue numbers (HD) had been derived from the DM numbers, those were also
corrected as necessary.

Although the "Henry Draper Extension" (Cannon 1925-1936) stars from "Harvard
Annals", Volume 100, having DM numbers listed in the original catalog, were
included in the SAO, those listed with AG numbers only (Astronomische
Gesellschaft, zones +50 to +54 degrees, Harvard, Rogers 1892; zones +55 to +59
degrees, Helsingfors-Gotha, Kruger 1890) had not been cross identified and
inserted into the machine version. The "Yale Zone Catalogues" (YZ, Barney et al.
1959a, 1959b), which identify stars by their AG numbers, but also give
corresponding DM numbers, were used to cross identify the AG stars. This was
accomplished by using the magnetic tape versions of the YZ and HD catalogs and
matching the stars by machine. A cross index of Henry Draper Extension stars
from "Harvard Annals", Volume 112 (Cannon and Walton Mayall 1949) and DM numbers
(Bonnet 1978) was used to insert HDE numbers from the final HD volume.

Since the GC (Boss 1937) numbers in the "SAO-HD-GC-DM Cross Index" had been
assigned by comparing with HD numbers in the GC, stars without HD numbers in the

                                     1 - 2

Cross Index were missing GC identifications. The magnetic tape file of the GC
was therefore searched by DM number for all stars having no GC numbers in the
Cross Index. Additional GC numbers were found manually (by position) for the few
remaining stars without DM numbers. Fourteen GC stars were found not to be in
the SAO Catalog. HD numbers in the GC were then compared with their counterparts
in the Cross Index for stars in common, leading to the detection and correction
of a number of additional errors.

The catalog contains a numerical code appended to each HD number. The code
originally followed the convention of the "Strasbourg Catalog of Stellar
Identifications" (CSI, Ochsenbein et al. 1981) which assigned the numbers
1, 2, ... for individual components of multiple systems and the digit 9 if two
contiguous HD stars are included in the entry (the lower HD number is usually
given with code 9). Since the component codes were assigned to CSI entries
without regard to letter designations, and because letter designations have now
been added, the HD code was changed to a consistent indication of major
contamination of the spectral type of the component to which the entry applies
by the spectrum of another star (see Table 2). A visual magnitude difference of
0.3 mag was used as the limit for which contamination was indicated. Although
photographic magnitudes would have been more appropriate, the visual magnitudes
in the SAO appeared to be more consistent.


Many HD numbers were added to the "SAO-HD-GC-DM Cross Index" and subsequently to
the SAO, and quite a few incorrect HD numbers were changed. The SAO already
contained spectral types for many of these stars; those types were compared with
the types in the HD, and discrepancies were corrected only where it seemed
desirable. For stars with new HD numbers and no spectral types in the SAO, the
latter were inserted using the machine version of the HD for the main catalog
and the first extension. Spectral types were read from the charts of the second
extension ("Harvard Annals" 112) and approximately 5000 inserted manually; types
were also inserted for other HD stars for which they were missing in the SAO.
For components of multiple stars, spectral types were added or removed according
to the likelihood that the star contributed to the HD type.

Following completion of the Cross Index, all appropriate cross-identification
data were replaced in the 1984 SAO. Additional corrections involving the SAO
only were then made. In certain cases, SAO positions had been found in error,
but correct positions in the SAO system could not have been derived without a
re-reduction of all the original data. Since this would clearly have been
impracticable, positions were taken from the "Cape Photographic Catalogues" for
1950.0 (CPC). (Errata for the CPCs have been published in the zone catalog for
-80 to -90 degrees (Stoy 1968)). The CPC proper motions were applied to the
positions at epoch to bring them to epoch 1950.0.

In the 1984 version, a total of 12,373 SAO records was corrected or
supplemented with 17,915 individual data changes.  All changes are listed in
the accompanying file of corrections (see Section 4).  Changes in the 1989
version, from the 1984 version, are given in Table 13, and those additional
data changed in the 1990 version are given in Table 15.

As noted in the introduction, Clay Smith provided positions and proper motions
at equinox and epoch J2000.0 and on the system of the FK5.

                                     1 - 3
 
                           SECTION 2 - FILE CONTENTS


A byte-by-byte description of the contents of the machine-readable SAO Catalog
is given in Table 1. The suggested format specifications apply to FORTRAN
formatted read statements and can be modified depending upon individual
programming and processing requirements. All data fields with primary A-format
specifications are blank for missing data; hence the alternate numerical
specifications used for machine searches will produce zero values. Data are
always present in fields for which primary numerical formats are given, except
where specifically noted.


Table 1.  File Contents.  Smithsonian Astrophysical Observatory Star
          Catalog,  version 1989.


                Suggested
Byte(s)  Units   Format           Description


  1-  6   ---     I6              SAO number.

      7   ---     A1              "D" if this SAO entry refers to a duplicate
                                   star from the catalog.

  8-  9  hours    I2               Right ascension B1950.0 equinox and epoch.

 10- 11   min     I2               RA

 12- 17   sec     F6.3             RA

 18- 24  sec/yr   F7.4             Annual proper motion in RA.

 25- 26   0.001   I2(F2.3)         Standard deviation of pm (RA).
         arcsec/yr

     27   ---     A1               A "+" or "-" to indicate that the minutes of time
                                   associated with the seconds portion of RA (bytes
                                   28-33) must be increased or decreased by 1,
                                   respectively; otherwise blank (if RA2 is the same
                                   minute as RA sec in bytes 12-17).

 28- 33   sec     F6.3             Seconds portion (RA2) of RA at original epoch,
                                   precessed to 1950.0 (i.e. 1950 position
                                   modified by proper motion).

 34- 35  0.01     I2(F2.2)         Standard deviation of RA2.
        arcsec/yr

 36- 41   years   F6.1             Epoch of RA2.



                                     2 - 1

Table 1.  (continued)


                Suggested
Byte(s)  Units   Format            Description


     42   ---     A1               Sign of declination.

 43- 44   deg     I2               Declination B1950.0 equinox and epoch.

 45- 46  arcmin   I2               Dec

 47- 51  arcsec   F5.2             Dec

 52- 57  arcsec/  F6.3             Annual proper motion mu(delta).
          yr

 58- 59  0.001    I2(F2.3)         Standard deviation of mu(delta).
        arcsec/yr

     60   ---     A1               A "+" or "-" to indicate that the arcminutes
                                   associated with the arcseconds portion of Dec
                                   (bytes 61-65) must be increased or decreased by 1,
                                   respectively; otherwise blank (if Dec2 is in the
                                   same minute as Dec in bytes 47-51).

 61- 65  arcsec   F5.2             Seconds portion (Dec2) of Dec at original
                                   epoch, precessed to 1950.0 (i.e. 1950
                                   position modified by the proper motion).

 66- 67   0.01    I2(F2.2)         Standard deviation of Dec2.
         arcsec

 68- 73   years   F6.1             Epoch of Dec2.

 74- 76   0.01    I3(F3.2)         Standard deviation of position at epoch
         arcsec                    1950.0.

 77- 80    mag    F4.1             Photographic magnitude mpg (99.9 if no value
                                   present).  When both magnitude fields are
                                   99.9, the miscellaneous code (byte 95) should
                                   be checked for possible variability, in which
                                   case magnitudes may not be reported.

 81- 84    mag    F4.1             Visual magnitude mv (99.9 if no value
                                   present).

 85- 87    ---    A3               Spectral type ("+++" for composite spectra).

 88- 89    ---    I2               Coded source of visual magnitude (see
                                   Table 3).


                                      2 - 2

Table 1.  (continued)


                Suggested
Byte(s)  Units   Format            Description

 90- 91   ---     I2               Coded source of star number and footnotes
                                   (see Table 4).

     92   ---     I1               Coded source of photographic magnitude
                                   (see Table 5).

     93   ---     I1               Coded source of proper motions (see Table 6).

     94   ---     I1               Coded source of spectral type (see Table 7).

     95   ---     I1               Coded miscellaneous remarks for duplicity and
                                   variability (see Table 8).

     96   ---     I1               Accuracy of visual magnitude:  0 indicates
                                   that the magnitude in the source catalog is
                                   reported to 0.00 mag; 1 to 0.0 mag.

     97   ---     I1               Accuracy of photographic magnitude same coding
                                   as for byte 96.

 98- 99   ---     I2               Code for source catalog (see Table 9).

100-104   ---     I5               Number in source catalog.

105-106   ---     A2               Durchmusterung (DM) identification
                                   BD  Bonner Durchmusterung
                                   CD  Cordoba Durchmusterung
                                   CP  Cape Photographic Durchmusterung
                                   All DM fields are blank if no DM
                                   identification is present.

    107   ---     A1               Sign of DM zone.

108-109   ---     I2 (A2)          DM zone.

110-114   ---     I5 (A5)          DM number.

115-116   ---     A2               Component identification if there are two or
                                   more SAO stars having the same DM number. For
                                   multiple systems included in the "Index
                                   Catalogue of Visual Double Stars" (IDS, see
                                   Worley 1980) the IDS components are given;
                                   for non-IDS stars, components were assigned
                                   on the basis of magnitude. If two components
                                   of southern double stars are listed, DM
                                   numbers from different catalogs are often
                                   quoted for the components. In these cases,
                                   component identifications are usually given
                                   without changing the DM numbers.

                                      2 - 3
Table 1.  (concluded)


                Suggested
Byte(s)  Units   Format            Description

    117   ---     A1               Lower case letter identification for BD
                                   supplemental stars (Warren and Kress 1980).

118-123   ---     A6 (I6)          Henry Draper (HD or HDE) Catalogue number

    124   ---     A1 (I1)          HD Code (1, 2, ... for component
                                   identifications where more than one star has
                                   the same HD number (not necessarily
                                   equivalent to A, B, ... or to the component
                                   identifications in the IDS; see Table 2))

125-129   ---     A5 (I5)          Number in the "General Catalogue of 33342
                                   Stars for 1950" (GC, Boss 1937).

130-139    rad    F10.8            Right ascension (B1950.0).

140-150    rad    F11.8            Declination (B1950.0).

151-152   hours   I2               Right ascension for J2000.0.

153-154    min    I2               RA

155-160    sec    F6.3             RA

161-167   sec/yr  F7.4             Annual proper motion in right ascension
                                   for J2000.0.

    168    ---    A1               Sign of declination.

169-170    deg    I2               Declination for J2000.0.

171-172   arcmin  I2               Dec

173-177   arcsec  F5.2             Dec

178-183   arcsec/ F6.3             Annual proper motion in declination
            yr                     for J2000.0.

184-193    rad    F10.8            RA (J2000.0)

194-204    rad    F11.8            Dec (J2000.0)


                                     2 - 4

Table 2 gives a detailed description for each HD code that can occur
in byte 124 of a data record.

Table 2.  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.










































                                      2 - 5


Tables 3 through 9 give data sources and duplicity / variablility codes.

Table 3.  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 (Table 8) when using
magnitudes. When blank, code = 0 and field = 99.9.












                                     2 - 6

Table 4.  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.


Table 5.  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.




                                     2 - 7

Table 6.  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)


Table 7.  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.













                                     2 - 8

Table 8.  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.
































                                     2 - 9


Table 9.  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







                                    2 - 10

                       SECTION 3 - FILE CHARACTERISTICS

The information in Table 10 is sufficient for a user to describe the indigenous
characteristics of the machine-readable Smithsonian Astrophysical Observatory
Star Catalog, Version 1990 to a computer. Not included is information easily
varied from installation to installation, such as block size (physical record
length), blocking factor (number of logical records per physical record), total
number of blocks, tape density, number of tracks, and internal coding (EBCDIC,
ASCII, etc.). These parameters should always be transmitted if secondary copies
of the catalog are supplied to other users or installations.


Table 10.  File Characteristics.  "Smithsonian Astrophysical Observatory Star
           Catalog", Version 1989.


NUMBER OF FILES  . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

LOGICAL RECORD LENGTH (BYTES)  . . . . . . . . . . . . . . . . . . . . 204

TOTAL NUMBER OF LOGICAL RECORDS  . . . . . . . . . . . . . . . . .  258997

































                                     3 - 1

              SECTION 4 - REMARKS, ACKNOWLEDGMENTS AND REFERENCES


As mentioned in Section 1, the individual data corrections, additions and
changes included in the 1984 version of the SAO Catalog number 17,915, with
12,373 records (4.8%) having at least one change.  Since many of the changes
involve corrections to data given in previously published catalogs, it is
important for a user to have access to the individual changes if a discrepancy
is found between this catalog and a previously published one.  For this reason,
we have prepared a complete table of all changes made to the previous version
to produce the 1984 version as well as tables of additional changes in the 1989
and 1990 versions.  The first corrections and changes table was prepared by
comparing the uncorrected file against the new version with a computer program
which compared the data fields one by one and produced a formatted changes
table.  The complete table for the 1984 version is given in the accompanying
file of corrections.  If a data entry is blank in either version, it is blank
for the corresponding item in the table.  The column labeled "S" gives the
source of the change, as defined in Table 11 by its numerical code.  Table 13
lists the changes in the 1989 version and Table 15 lists the changes in the
1990 version.  Table 14 explains the codes for the source of the 1989 changes
and table 16 gives the sources of those corrections in the 1990 version that
did not result from the ADC checking of Mr. Rappaport's suggested changes.

Table 11.  References for Changes to the SAO Catalog, Version 1984.

Code   Reference(s)

  1    Haramundanis, K. undated,  "Errata Sheet for the SAO Star Catalog";
         1971, Note on SAO Catalog Errata (January).

  2    Stein, W. L. and Rudisill, J. C., 1977, "Introduction to the
         Dahlgren General Catalog", Naval Surface Weapons Center
         NSWC/DL TR-3607.

       Stein, W. L. 1978, in Bischoff, M., Bull. Inf. Cent. Donnees
         Stellaires, No. 14, 2; No. 15, 103.

       Stein, W. L., private communication.

  3    Bischoff, M. 1978, Bull. Inf. Cent. Donnees Stellaires, No. 14,
       2; No. 15, 103.

  4    Hoffleit, D., private communication.

  5    Parsons, S. B. 1977, Bull. Inf. Cent. Donnees Stellaires,
       No. 12, 41.

  6    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.

                                      4-1

  7    Houziaux, L. and Blondelot-Lickes, J. 1970, Centre Univ. Mons,
         Fac. Sci., Dept. Astrophys., Communication No. 13.

  8    Stoy, R. H. 1968, "Cape Photographic Catalogue for 1950.0",  Zones
         -80 to -90 degrees, Ann. Cape Obs. 22 (London: Her Majesty's
         Stationery Office).

  9    McLaughlin, S. F., private communication.

 10    Bonnet, R. 1978, "Cross Identifications of HDE Stars", Bull. Inf.
         Cent. Donnees Stellaires, No. 15, 155. Magnetic tape version,
         CDS Strasbourg catalog number 4008.

 11    Warren, W. H. Jr. and Kress, K. 1980, Catalog of Supplemental
         Stars to the Bonner Durchmusterung, Astron. Data Center Bull. 1, 19.

 12    Errors and additions from the ADC work.

 13    Schmidtke, P. C., private communication.

 14    Herald, D. 1979, Occultation Newsl. 2, 49.


Table 12 includes further notes on entries in the microfiche table for which
additional explanations are considered useful to clarify the reasons for
certain changes.


Table 12.  Explanatory Notes to Individual Changes.


  SAO   Note(s)

  6404  The GC incorrectly identifies this star as BD+76 309;
        GC 11190 is BD+76 309, while this star is +77 309.

  9947  This star is misidentified as BD+70 1162 in the GC, as it is in
        the IDS and ADS (Aitken 1932).  Source 3 corrects the DM number
        to +70 1161, assuming that the double entry for +70 1161
        represents the two components of the double star.  This is not
        the case.  SAO 9949 is a duplicate entry and should be deleted.

 15097  The GC incorrectly lists this star as BD+65 761.  It is
        actually +65 751, while +65 761 is SAO 15120, which does not
        appear in the GC.

 17589  The GC incorrectly identifies this star as BD+68x 936, whereas
        it is actually +69 936.

                                      4-2


 23221  Source 1 incorrectly gives this star as BD+53 568a.  It is
        actually +52 568a.

 SAO    Note(s)

 24753  This star is listed as BD+57 825 in several catalogs.  It is
        not in the proper position for the BD star, however.  There is
        a star at the SAO position on photographs, but it is not in the
        BD.


 29370  These corrections are probably in error.  The BD gives +54 1724
 29372  as being SW of +54 1725 and lists both star as magnitude 7.5.
        The SAO, AGK3 and IDS list the brighter star (delta m = 0.6 mag)
        as SE.  the HD also lists the brighter star as south, but gives
        the same right ascension for both stars.  The IDS identifies the
        brighter star as BD+54 1724, as do the HD and SAO, but the AGK3
        reverses the DM numbers, listing the brighter star as +54 1725.

101858  Sources 2 and 3 suggested changing this stars to BD+17 2945.
        It is part of a triple system of which C, the fainter, more
        distant component, is +17 2945.  SAO 101858 and 101859 appear
        to be the A and B components, respectively, of +17 2946.

238176  The GC is in error.  GC 14513 is CP-54 3795 and is not in the
        HD.  GC 14517 is CP-54 3797, which is HD 91593.


Table 13.  1989 Changes to the 1984 Version.


 No.    Field      For          Read                 S

 5840   DM No.    BD+78 222                          21
 9160   DM No.    BD+69 993a    BD+69 993            21
 9773   DM No.    BD+77 778                          21
12509   Spectrum  B:            Bp                   22
20758   DM No.    BD+63 2030    BD+63 2030a          21
23221   DM No.    BD+53 568a    BD+52 568a           21
27123   DM No.    BD+57 1199    BD+57 1194           21
29370   DM No.    BD+54 1725    BD+54 1724           21
29372   DM No.    BD+54 1724    BD+54 1725           21
39436   Spectrum  B:            Bp                   22
45289   DM No.    BD+46 2005a   BD+46 2005           21
56771   Spectrum  GO            G0                   22
62236   DM No.    CD+31 2180    BD+31 2180           21
64711   DM No.    BD+40 2872    BD+39 2872           21
74667   DM No.    BD+28 255     BD+28 225            21
76943   DM No.    BD+28 741     BD+28 742            21

                                      4-3

Table 13.  (continued)


No.     Field     For           Read                 S

76943   HD No.    HD 32479                           21
76944   DM No.    BD+28 742     BD+28 741            21
76944   HD No.                  HD 32479             21
82706   DM No.    CD+28 2193    BD+28 2193           21
85564   DM No.    BD+29 3149a   BD+29 3149           21
85567   DM No.    BD+29 3149    BD+29 3149a          21
86043   DM No.    CD+29 3259    BD+29 3259           21
94818   HD No.    HD 247073                          23
97434   RA        7h56m2.355s   7h56m4.172s          24
97434   PM (RA)   +0.0021s/a    +0.0302 s/a          24
107156  DM No.    BD+13 4710    BD+13 4714           21
111240  DM No.    BD+ 0 602     BD+ 0 603            21
114916  DM No.    BD+ 1 1687    BD+ 1 1686           21
128522  DM No.    BD- 0 5077    BD+ 0 5077           21
129898  DM No.    BD- 0 361     BD- 0 361a           21
130238  PM (RA)   0.03s/a       +0.019:s/a           25
130238  PM (DEC)  1.30"/a       -0.08:"/a            25
131091  DM No.    BD- 7 787     BD- 7 788            21
133461  Record                  Delete               23
142402  Record                  Delete               23
156969  HD No.                  HD 103314            21
156999  HD No.    HD  103314                         21
159442  DM No.    CD-19 4188    BD-19 4188           21
159682  DM No.    CD-19 4307    BD-19 4307           21
163131  DM No.    BD-12 5991    BD-12 5591           21
163131  HD No.    HD 204013     HD 188763            21
167662  DM No.    CD-30 804     CD-29 804            21
172151  DM No.    BD-20 1550    BD-21 1550           21
172631  Record                  Delete               23
172821  DM No.    CD-28 3844    CD-28 3744           21
178737  DM No.    BD-21 3161    BD-20 3161           21
178737  HD No.    HD 93814      HD 89913             21
179258  DM No.    BD-20 3161    BD-21 3161           21
179258  HD No.    HD 89913      HD 93814             21
180619  Record                  Delete               23
181584  Record                  Delete               23
185579  DM No.    CD-27 11769   CD-27 11768          21
186318  DM No.    CD-23 13936   CD-23 13937          21
186419  DM No.    CD-26 12900   CD-26 12898          21
186717  Record                  Delete               23
187331  DM No.    BD-22 13325   CD-22 13325          21
190341  DM No.    BD-22 15388   CD-22 15388          21
192236  DM No.    CD-22 16507   CD-22 16508          21
193858  Record                  Delete               23
193896  Record                  Delete               23



                                      4-4

Table 13.  (concluded)


No.     Field     For           Read                 S

198195  DM No.    BD-34 3755    CD-34 3755           23
201368  DM No.    CD-37 6528B                        21
204943  DM No.    CD-31 10729   CD-31 10727          21
206001  DM No.    CD-38 9673    CD-38 9693           21
208948  DM No.    CD-36 11642   CD-36 11632          21
209763  DM No.    CD-31 15539   CD-31 15149          21
209763  HD No.    HD 165930     HD 165725            21
210778  DM No.    CD-38 13224   CD-38 13239          21
211312  DM No.    CD-36 13215   CD-37 13215          21
213279  DM No.    CD-32 16734                        21
215182  Record                  Delete               23
216710  DM No.    BD-42 1425    CD-42 1425           21
220069  Spectrum  B:            Bp                   22
222287  Record                  Delete               23
223213  DM No.    CP-49 4828    CP-49 4827           21
226867  DM No.    CD-45 10733   CD-45 10731          21
226867  GC No.                  GC 22215             21
226868  DM No.    CP-45 8001C   CP-45 8001           21
226868  GC No.    GC 22215                           21
227380  Record                  Delete               23
227535  DM No.    CD-44 11300   CD-43 11300          21
228027  Record                  Delete               21
228306  Record    Delete        Keep                 21
229059  Record                  Delete               23
232734  RA        2h20m50.218s  2h20m53.218s         24
234389  Record                  Delete               23
236668  Record                  Delete               23
238148  DM No.    CP-53 3909    CP-53 3909B          26
238511  Record                  Delete               23
240305  Record                  Delete               23
241167  Record                  Delete               23
242605  Record                  Delete               23
242962  Record                  Delete               23
244399  HD No.    HD 153772     HD 153771            26
244399  GC No.    GC 22982                           21
244400  HD No.                  HD 153772            26
244400  GC No.                  GC 22982             21
244725  DM No.    CD-55 8100    CP-55 8100           21
246634  DM No.    CP-51 10511   CP-51 11511          21
250957  Dec.      -60d51'49.26" -60d31'49.26"        24
251166  DM No.    CP-66 1447    CP-66 1453           21
251166  HD No.    HD 94494                           21
252071  DM No.    CP-59 4544                         21
252312  Spectrum  B:            Bp                   22
256721  DM No.    CP-73 746     CP-73 745            21
256935  DM No.                  CD-74 677            21
258552  DM No.    CP-83 398     CP-80 398            21

                                4-5


All communications resulting in the changes in Table 13 are unpublished. For
13028, it is apparent that the proper motions are in error but accurate values
are unavailable. In addition to the changes noted in Table 13, R. E. Reaves
pointed out that plus signs were missing in bytes 27 and 60, that minus signs
were occasionally found in byte 61, and that the seconds of arc field for the
declinations sometimes read 60.00. These problems have been corrected.


Table 14.  Sources for Changes in the 1989 Version.




Code                    Source


21                      T. Lederle
22                      R. E. Reaves
23                      T. Lederle and ADC
24                      T. Lederle and T. E. Corbin
25                      H. Jahreiss and T. E. Corbin
26                      ADC
































                                 4-6

   Table 15.  Changes to the SAO since the 1989 Version

  +--------------+-------------------+--------------+-------------+
  |              |                   |              |             |
  | SAO Number   |      Field        |     For      |    Read     |
  |              |                   |              |             |
  +--------------+-------------------+--------------+-------------+
  |     15475    |     DM Number     |   +66  717   |             |
  |     19985    |     DM Number     |   +61 2278   |  +61 2277   |
  |     19985    |     HD Number     |              |   211871    |
  |     27062    |    Spec. Type     |       5      |     R5      |
  |     27100    |    Spec. Type     |       5      |     R5      |
  |     31951    |    Spec. Type     |       P      |     Pd      |
  |     32162    |     DM Number     |   +57 2104   |  +57 2103   |
  |     32162    |     HD Number     |     239271   |             |
  |     35236    |     DM Number     |   +56 2966   |  +56 2967   |
  |     35236    |     HD Number     |     219134   |             |
  |     40312    |     DM Number     |   +43 1261   |  +43 1260   |
  |     40314    |     DM Number     |   +43 1260   |  +43 1261   |
  |     51472    |     DM Number     |   +46 3506   |  +46 3505   |
  |     52114    |     DM Number     |   +48 3759   |  +48 3757   |
  |    187331    |     DM Catalog    |      CD      |      BD     |
  |    190341    |     DM Catalog    |      CD      |      BD     |
  |    209822    |     DM Number     |   3512351   |  3512350   |
  |    211074    |     DM Number     |   3713108   |  3713109   |
  |    212391    |     DM Number     |   3018140   |  3018139   |
  |    212470    |  Mu Dec. - J2000  |    0.003    |             |
  |    215732    |     DM Number     |   43  611   |  43  612   |
  |    217573    |     HD Number     |              |    39563    |
  |    219568    |     DM Catalog    |      CP      |      CD     |
  |    219568    |     HD Number     |     39563    |    68602    |
  |    227379    |     HD Number     |    152233    |             |
  |    227380    |     HD Number     |              |    152233   |
  |    227380    |    Delete Code    |       D      |             |
  |    228306    |  RA Sec at Epoch  |    36.692    |   36.693    |
  |    232345    |     DM Number     |   51  312   |  51  311   |
  |    232345    |     HD Number     |       7456   |     7455    |
  |    232346    |     DM Number     |   51  311   |  51  312   |
  |    232346    |     HD Number     |       7455   |     7456    |
  |    234535    |    Spec. Type     |       GO     |     G0      |
  |    239348    |     DM Number     |   58 3829   |  58 3823   |
  |    239348    |     HD Number     |    307183    |   102117    |
  |    244400    |    Supp. Code     |       1      |             |
  |    244400    |     HD Number     |    537720    |    153772   |
  |    244400    |      HD Code      |       2      |      0      |
  |    244400    |     GC Number     |     29820    |    22982    |
  +--------------+-------------------+--------------+-------------+


                                     4 - 7


   Table 16.  Sources of Changes since 1989 other than DM Numbers

  +--------------+------------------------+-----------------------+
  |              |                        |                       |
  | SAO Number   |         Field          |        Source         |
  |              |                        |                       |
  +--------------+------------------------+-----------------------+
  |    27062     |      Spec. Type        |      Allan Moluf      |
  |    27100     |      Spec. Type        |      Allan Moluf      |
  |    31951     |      Spec. Type        |      ADC              |
  |    56597     |      Declination       |      Allan Moluf      |
  |    75878     |      Dec Sec at Epoch  |      William M. Owen  |
  |    84129     |      Magnitudes        |      William M. Owen  |
  |    92548     |      Magnitudes        |      David W. Dunham  |
  |    97645     |      HD Number         |       A. R. Peters    |
  |    97646     |      HD Number         |       A. R. Peters    |
  |   143378     |      J2000 Positions   |      Clayton A. Smith |
  |   187331     |      DM Catalog        |      Carl Cole        |
  |   190341     |      DM Catalog        |      Carl Cole        |
  |   194834     |      Spec. Type        |      Allan Moluf      |
  |   208759     |      Mu Dec. - J2000   |      Allan Moluf      |
  |   208795     |      Mu Dec. - J2000   |      Allan Moluf      |
  |   212470     |      Mu Dec. - J2000   |      Allan Moluf      |
  |   217573     |      HD Number         |      ADC              |
  |   219568     |      DM Catalog        |      ADC              |
  |   219568     |      HD Number         |      S. F. McLaughlin |
  |   227379     |      HD Number         |      A. R. Peters     |
  |   227380     |      Delete Code       |      ADC              |
  |   227380     |      HD Number         |      A. R. Peters     |
  |   228306     |      RA Sec at Epoch   |      ADC              |
  |   234535     |      Spec. Type        |      Allan Moluf      |
  |   244400     |      Misalignment      |      Allan Moluf      |
  +--------------+------------------------+-----------------------+
  |NOTE: The  magnitudes  for 84129 and 92548 are from the SIMBAD |
  |data bank of the Centre de Donnees Astronomiques de Strasbourg.|
  +--------------+------------------------+-----------------------+


ACKNOWLEDGMENTS

We wish to express our appreciation to N. J. Schofield Jr., who worked on an
early phase of the SAO project in connection with the revised "SAO-HD-GC-DM
Cross Index", and to D. Hoffleit, S. F. McLaughlin, R. E. Reaves, P. C.
Schmidtke and W. L. Stein for communicating errors. We also thank the several
people who pointed out additional errors, and T. E. Corbin for checking
data for several stars in other catalogs and Mr. Rappaport for sending
us the extensive list of possible problems in the DM numbers assigned
in the SAO. We also thank those listed in Table 16 on page 4 - 7.

for alerting us to other errors. Especially significant was the work
of T. Lederle (Astronomisches Rechen-Institut, Heidelberg), who analyzed
a large number of cross identifications for Durchmusterung stars, provided
a large list of possible errors, and worked with us to improve the changes,
which were then inserted into the 1989 version.

                                     4 - 8


Finally, the new J2000 version of the catalog owes much to the work of C.A.
Smith (U.S. Naval Observatory), who computed the J2000 positions and proper
motions and added them to the data records.


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Barney, I., Hoffleit, D. and Jones, R. B. 1959a, Catalogue of the Positions and
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