VII/80 The HEAO A-1 X-Ray Source Catalog (Wood+, 1984)
The HEAO A-1 X-Ray Source Catalog
Wood K.S., Meekins J.F., Yentis D.J., Smathers H.W., McNutt D.P.,
Bleach R.D., Byram E.T., Chubb T.A., Friedman H., Meidav M.
<Astroph. Jour. Suppl. 56, 507-649 (1984)>
=1984ApJS...56..507W 1984ApJS...56..507W
ADC_Keywords: X-ray sources
Mission_Name: HEAO
Abstract:
The HEAO A-1 X-Ray Source Catalog is a compilation of data for 842
sources detected with the U. S. Naval Research Laboratory Large Area
Sky Survey Experiment flown aboard the HEAO 1 satellite. The data
include source identifications, positions, error boxes, mean X-ray
intensities, and cross identifications to other source designations.
Introduction:
The primary objective of the Naval Research Laboratory (NRL) Large
Area Sky Survey Experiment (LASS) flown aboard the HEAO 1 satellite
was to conduct an all-sky survey for the brightest X-ray sources in
the energy range 0.25 to 25 keV. The instrumentation consisted of an
array of large proportional counter modules with collimators of
varying fields of view and with sufficient sensitivity to detect
sources as faint as 0.25 mu.Jy at 5 keV, assuming a Crab-like spectrum
(1.1 muJy at 5 keV = 1 UFU for a Crab-like spectrum). Full sky
coverage was achieved in the first 6 months of the mission by
continuously scanning great circles perpendicular to the Earth-Sun
line. The HEAO A-1 catalog results from the 6-month survey and, thus,
covers the whole sky. For additional information concerning the NRL
LASS instrument, the data analysis procedures, characteristics and
limitations of the source data, and a discussion of X-ray source
classes, the source publication should be consulted.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
sources.dat 303 842 The data
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Byte-by-byte description of file: sources.dat
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Bytes Format Unit Label Explanations
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1- 10 A10 --- name Source designation (1H)
12- 17 F6.2 deg RAdeg Right ascension 1950 in degrees
19- 20 I2 h RAh RA (B1950.0) hours
22- 23 I2 min RAm RA (B1950.0) minutes
25- 26 I2 s RAs RA (B1950.0) seconds
28- 33 F6.2 deg DEdeg Declination 1950 in degrees
35 A1 --- DE- Declination sign
36- 37 I2 deg DEd Dec (1950.0) degrees
39- 40 I2 arcmin DEm Dec (1950.0) minutes
42- 43 I2 arcsec DEs Dec (1950.0) seconds
45- 50 F6.2 deg GLON Galactic longitude
52- 57 F6.2 deg GLAT Galactic latitude
59- 64 F6.2 deg ELON Ecliptic longitude
66- 71 F6.2 deg ELAT Ecliptic latitude
73- 78 F6.2 deg RA1 Right ascension_1 (1)
80- 85 F6.2 deg DE1 Declination_1. (1)
87- 92 F6.2 deg RA2 Right ascension_2 (1)
94- 99 F6.2 deg DE2 Declination_2 (1)
101-106 F6.2 deg RA3 Right ascension_3 (1)
108-113 F6.2 deg DE3 Declination_3 (1)
115-120 F6.2 deg RA4 Right ascension_4 (1)
122-127 F6.2 deg DE4 Declination_4 (1)
129-133 F5.3 deg2 area Area of error box
135-141 F7.4 ct/cm2/s flux Flux (2)
143-148 F6.4 ct/cm2/s e_flux Flux error (2)
150-161 A12 --- name2 Alternate designation (X-ray) (3)
163-174 A12 --- name3 Alternate designation (X-ray) (3)
176-188 A13 --- name4 Alternate designation (X-ray) (3)
189-200 A12 --- name5 Alternate designation (X-ray) (3)
202-213 A12 --- name6 Alternate designation (X-ray) (3)
215-226 A12 --- name7 Alternate designation (X-ray) (3)
228-239 A12 --- name8 Alternate designation (X-ray) (3)
241-255 A15 --- name9 Alternate desig. (non-X-ray) (3)
257-271 A15 --- name10 Alternate desig. (non-X-ray) (3)
273-287 A15 --- name11 Alternate desig. (non-X-ray) (3)
289-303 A15 --- name12 Alternate desig. (non-X-ray) (3)
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Note (1):
The source coordinates (center of error box) are given in degrees and
in sexagesimal form. The subscripted right ascensions and declinations
(right ascension_1-4, declination_1-4) give the positions of the 95
percent confidence error box surrounding each source. All positions
are for equinox B1950.0.
Note (2):
The apparent intensity of the source in counts/sq.cm/s for 0.5 - 25
keV. The determination of the errors is described in Section III of
the source reference (Wood et al. 1984). As explained in that paper,
an intensity of 10**-3. counts/sq.cm/s, which is the limiting flux in
the catalog, corresponds to 3.3*10**-12 ergs/sq.cm/s in 2-10 keV, both
for a Crab-like spectrum, meaning that 10**-3 counts/sq.cm/s in HEAO
A-1 is equivalent to 0.20 UFU or to 0.22 muJy at 5.2 keV, again for a
Crab-like spectrum.
Note (3):
The first seven fields (bytes 150-239) contain alternate designations
of each source in other X-ray catalogs, while the last four fields are
for non-X-ray cross identifications. Catalog identifications and
references are given in Table 5 of the source paper. Cross
identifications were selected according to certain criteria. For X-ray
catalogs (4U, 2A, 1M, etc.), where error boxes of up to several
degrees are sometimes reported, the cross reference is given whenever
the other error box intersects the HEAO A-1 error box. Identifiers are
also given in certain cases where boxes do not strictly intersect but
are sufficiently close to suggest a possible relationship. The
criterion used is that the separation between box centers must be less
than the sum of the two largest dimensions. The designation XRS (not
included in Table 5, but described in text) is from Amnuel, Guseinov,
and Rakhamimov (1979), 4hich summarizes much of the older X-ray
literature.
Non-X-ray cross identifications were made on several bases. Whenever
an identification has been firmly established, for example, by a
precise position from a modulation collimator or from the Einstein
Observatory, it is always shown, but so are many additional tentative
identifications. Some of these have been suggested by earlier work (in
which case the earlier literature appears either in Table 5 or Table 6
of the source reference) and the remainder have been found by
searching the non-X-ray catalogs listed by the authors in their Table
5. Additional information on selection criteria will be found on page
647 of the source reference.
Whenever an (R) appears in the last field, additional references and
comments will be found in Table 6 of the source reference. Those
entries are intended primarily to provide a sketch of the basic
background and current state of knowledge concerning the sources, to
direct users to further literature, and to clarify ambiguities. They
are not intended to be a comprehensive bibliography and many
references are omitted. A special effort has been made to provide
cross references to other HEAO 1 literature wherever possible, since
other HEAO 1 observations are simultaneous with and complementary to
those in the catalog.
History:
The HEAO A-1 X-Ray Source Catalog was received on magnetic tape by the
National Space Science Data Center on 20 July 1984 from Dr. Kent S.
Wood of the Naval Research Laboratory. The tape was in VAX VMS BACKUP
format with variable length logical and physical records, plus special
control words (logical record length of each record in the first four
bytes.) A program was written to convert the records to fixed length
and the tape file was processed to disk storage on the IBM 3081
computer of the NASA Space and Earth Sciences Computing Center at
GSFC. The format of the file was identical to Table 4 of the published
catalog, meaning that there were 10 sources per group (page in the
published catalog), separated by column headings and blank records,
etc. All blank, text, and separator records were removed with an
editor, leaving just four records per source. A format was designed
that rearranged the data in logical order for a single record per
source structure, and a program was written and executed to reformat
the data. The advantages of the single record per source structure are
that all records are entirely uniform and the catalog can be sorted
and searched easily.
The original catalog contained the error box positions in both decimal
and sexagesimal form. The latter data were omitted during the
conversion in order to decrease the final record length, since the
sexagesimal data can be reconstructed easily from the decimal
positions given.
Acknowledgments:
Appreciation is expressed to Kent Wood for communicating about the
catalog in 1986 and for supplying multiple copies of the source paper.
Dr. Warren also thanks Dr. Wood for reviewing and commenting on a
draft version of this document.
The help of Jonathan McDowell of the Harvard-Smithsonian Center for
Astrophysics is also gratefully acknowledged. Dr. McDowell requested a
machine-readable copy of the catalog and made suggestions about the
proposed format, including the elimination of the redundant error box
positions in sexagesimal form.
The catalog was edited and the documentation prepared by Dr. Wayne
Warren. It was translated from Script to ASCII and put in the current
standard form by the undersigned.
References:
Amnuel, P. R., Guseinox, O. H., and Rakhamimov, Sh. Yu. 1979,
=1979ApJS...41..327A 1979ApJS...41..327A
Wood, K. S., Meekins, J. F., Yentis, D. J., Smathers, H. W., McNutt, D.
P., Bleach, R. D., Byram, E. T., Chubb, T. A., Friedman, H., and
Meidav, M. 1984, The HEAO A-1 X-Ray Source Catalog,
=1984ApJS...56..507W 1984ApJS...56..507W
(End) Nancy G. Roman [ADC/SSDOO] 08-May-1995