A description of the machine readable catalog, including detailed format and tape file characteristics, is given. The machine file is a computation of mean values for position and magnitude at a mean epoch of observation for each unique star in the Oxford, Paris, Bordeaux, Toulouse and Northern Hemisphere Algiers zone. The format was changed to effect more efficient data searching by position and additional duplicate entries were removed. The final catalog contains data for 997311 stars

Warren, W. H., Jr.

English

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WIDC-A-R&S
National Space Science Data Canter/
World Data Canter A For Rockets and Satellite!
83-16
DOCUMENTATION FOR THE MACHINE-READABLE VERSION
OF THE
SURVEY OF THE ASTROGRAPHIC CATALOGUE FROM 1 TO 31 DEGREES
OF NORTHERN DECLINATION (FRESNEAU 1983)
NOVEMBER 1983
https://ntrs.nasa.gov/search.jsp?R=19840015353 2020-03-20T22:09:54+00:00Z
NSSDC/WDC-A-R4S 83-16
DOCUMENTATION FOR THE MACHINE-READABLE VERSION
OF THE
SURVEY OF THE ASTROGRAPHIC CATALOGUE FROM 1 TO 31 DEGREES
OF NORTHERN DECLINATION (FRESNEAU 1983)
Wayne H. Warren Jr.
November 1983
National Space Science Data Center (NSSOC)/
World Data Center A for Rockets and Satellites (WDC-A-R&S)
National Aeronautics and Space Administration
Goddard Space Flight Center
Greenbelt, Maryland 20771
DOCUMENTATION FOR THE MACHINE-READABLE VERSION
OF THE
SURVEY OF THE ASTROGRAPHIC CATALOGUE FROM 1 TO 31 DEGREES
OF NORTHERN DECLINATION (FRESNEAU 1983)
ABSTRACT
A description of the machine-readable catalog, including detailed format and
tape file characteristics, is given. The machine file is a computation of
mean values for position and magnitude at a mean epoch of observation for each
unique star in the Oxford, Paris, Bordeaux, Toulouse and northern hemisphere
Algiers zones. The version described here is modified from the file received
from the author in that the format was changed to effect more efficient data
searching by position and additional duplicate entries were removed. The final
catalog contains data for 997311 stars.
TABLE OF CONTENTS
Section 1 - INTRODUCTION AND SOURCE REFERENCES
Section 2 - TAPE CONTENTS
Section 3 - TAPE CHARACTERISTICS
Section 4 - REMARKS, MODIFICATIONS, ACKNOWLEDGMENTS AND REFERENCES
Section 5 - SAMPLE LISTING
1-1
2-1
3-1
4-1
5-1
Table
1
2
LIST OF TABLES
Tape Contents
Tape Characteristics
2-1
3-1
SECTION 1 - INTRODUCTION AND SOURCE REFERENCE
The machine-readable version of the Aatpographic Catalogue (AC), Zones +01° to
+31° is the result of the determination of mean values for position and
magnitude at a mean epoch, of observation for each unique star in the original
catalogs. As is well known, the overlap of oriainal Carte du del plates
resulted in multiple entries for many stars in the final catalogs. The zones
considered here actually contained 1870976 individual measurements, from which
an initial catalog of mean data for 1025208 stars was derived. Following
preparation of a tape version ordered strictly by increasing right ascension
and decreasing declination, an additional 27897 apparently duplicate entries
were discovered. These entries were eliminated from the file according to a
separation criterion (see Section 4) to produce the final compilation. The
estimated mean standard errors for positional and magnitude data are 0.4 arc-
sec in each coordinate and 0.4 mag, respectively. For additional information
about the procedures used to compute the mean data, and basic results obtained
from the survey, such as completeness and the stellar distribution in the
northern Galactic hemisphere, the source references should be consulted.
This document describes the machine-readable catalog as it is currently
available from the Astronomical Data Center. It is intended to enable users
to read and process the data without problems and guesswork. A copy of this
document should accompany any machine-readable version of the catalog.
SOURCE REFERENCES
Fresneau, A. 1983a, Astvon. J. 88_, 1378.
Fresneau, A. 1983*, Proa. Statistical Methods in Astronomy Symposium,
Strasbourg, 13-16 September (ESA SP-201), p. 17.
1-1
SECTION 2 - TAPE CONTENTS
A byte-by-byte description of the contents of the machine-readable AC survey
catalog is given in Table 1. The suggested format specifications apply to
FORTRAN formatted read statements and are given primarily to specify data
types and to locate decimal points. Since all fields contain real numerical
data, i.e. all data are TYPE REAL and there are no blank fields, there is no
need to give default (null) values, so these are omitted from the table.
Table 1. Tape Contents. Survey of the Aatrographia Catalogue, Zones +01°
to +31°.
Byte(s)
1- 8
9-15
16-19
20-26
Units
0
o
mag
years
Suggested
Format
F8.4
F7.4
F4.1
F7.2
Description
Right ascension at mean epoch given,
equinox 1950.0
Declination at mean epoch given, equinox
1950.0
Mean photographic magnitude.
Mean epoch (unweighted) of all obser-
vations for this star.
2-1
SECTION 3 - TAPE CHARACTERISTICS
The information contained in Table 2 is sufficient for a user to describe the
indigenous characteristics of the machine-readable AC Survey compilation to a
computer. 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.) is not included. This
information should always be supplied if secondary copies are transmitted to
other users or installations.
Table 2. Tape Characteristics. Survey of the Astrographia Catalogue, Zones
+01° to +31°.
NUMBER OF FILES 1
LOGICAL RECORD LENGTH (BYTES) 26
RECORD FORMAT PB
TOTAL NUMBER OF LOGICAL RECORDS 997311
Fixed block length (last block may be short)
3-1
SECTION 4 - REMARKS, MODIFICATIONS, ACKNOWLEDGMENTS AND REFERENCES
The machine-readable AC Survey +01° to +31° was prepared from a tape supplied
by the author (A. Fresneau) during a visit to the Astronomical Data Center
(ADC) on 21 July 1983. As received, the file was found immediately to contain
some stars at various right ascensions which were apparently appended to the
file; however, a copy of the unsorted file was supplied to R. L. Mi 11 is of
Lowell Observatory, where he and L. H. Wasserman found additional groups of
stars out of RA order. The arrangement of the data was a result of the
reduction procedure (Fresneau 1983c) and should not have been unexpected.
Since the stars should be in some kind of rigorous order for data searching
purposes, the file was sorted by increasing RA with decreasing DEC as the
secondary sort field and increasing magnitude as the tertiary sort field. A
copy of the sorted file was then supplied to D. W. Dunham, who discovered
19873 records where all data were identical and 8024 records where differences
were too small to be accounted for by duplicity at AC resolution. A
separation criterion of 0?00031 was used to eliminate all stars whose
positions matched to within the limit in both RA and DEC. Since Dunham also
changed some of the faint magnitudes to suit his own applications, only his
program to eliminate duplicates was used to process the original sorted
version to produce the present file with no magnitude modifications and the
revised format. Although a more detailed analysis may be performed later, the
author concurs with the present method and production of this file for
distribution until such time as improved criteria may be established. It is
important to note and consider the fact that there are quite a few stars
present having magnitudes in the 16-18 range and others for which punching
errors have occurred, resulting in magnitudes such as 79.3, 79.5, 26.0, 75.3,
49.5, etc. (77 stars fainter than 16 magnitude, including definite punching
errors). These errors have not been corrected in the present machine version.
ACKNOWLEDGMENTS
Appreciation is expressed to A. Fresneau for making the machine-readable
catalog available for distribution from the ADC and for reviewing and
commenting on a preliminary version of this document. L. H. Wasserman and D.
W. Dunham kindly transmitted their findings back to the ADC, and Dr. Dunham
supplied his program for elimination of duplicate entries and a copy of his
modified version, formatted specifically for ADC purposes. The combined
efforts of these colleagues have produced an improved version of the machine
catalog for distribution to the astronomical community.
REFERENCES
Fresneau, A. 1983a, Astron. </. 88, 1378.
Fresneau, A. 1983i, Proo. Statistical Methods in Astronomy Syrnposiwn,
Strasbourg, 13-16 September (ESA SP-201), p. 17.
Fresneau, A. 1983c, personal communication.
4-1
SECTION 5 - SAMPLE LISTING
The sample listing given on the following pages contains logical data records
exactly as they are recorded on the tape. Groups of records from the
beginning and end of the catalog are illustrated. The beginning of each
record and bytes within the record are indicated by the column heading index
across the top of each page (digits read vertically).
5-1
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NASA
•National Aeronautics and
Space Administration
Goddard Space Flight Center
Greenbelt, Maryland 20771


Documentation for the machine-readable version of the Survey of the Astrographic Catalogue From 1 to 31 Degrees of Northern Declination (Fresneau 1983)

Documentation for the machine-readable version of the Survey of the Astrographic Catalogue From 1 to 31 Degrees of Northern Declination (Fresneau 1983)

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