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VII/80 The HEAO A-1 X-Ray Source Catalog (Wood+, 1984)
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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
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ADC_Keywords: X-ray sources
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 Units Label Explanations
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1- 10 A10 --- name Source designation (1H)
12- 17 F6.2 deg RA Right ascension (RA) 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 DE Declination (Dec) 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 long Ecliptic longitude
66- 71 F6.2 deg lat Ecliptic latitude
73- 78 F6.2 deg RA1 *Right ascension_1
80- 85 F6.2 deg DE1 *Declination_1.
87- 92 F6.2 deg RA2 *Right ascension_2
94- 99 F6.2 deg DE2 *Declination_2
101-106 F6.2 deg RA3 *Right ascension_3
108-113 F6.2 deg DE3 *Declination_3
115-120 F6.2 deg RA4 *Right ascension_4
122-127 F6.2 deg DE4 *Declination_4
129-133 F5.3 deg2 area Area of error box
135-141 F7.4 cm2/s flux *Flux
143-148 F6.4 cm2/s e_flux *Flux error
150-161 A12 --- name2 *Alternate designation (X-ray)
163-174 A12 --- name3 *Alternate designation (X-ray)
176-188 A13 --- name4 *Alternate designation (X-ray)
189-200 A12 --- name5 *Alternate designation (X-ray)
202-213 A12 --- name6 *Alternate designation (X-ray)
215-226 A12 --- name7 *Alternate designation (X-ray)
228-239 A12 --- name8 *Alternate designation (X-ray)
241-255 A15 --- name9 *Alternate designation (non-X-ray)
257-271 A15 --- name10 *Alternate designation (non-X-ray)
273-287 A15 --- name11 *Alternate designation (non-X-ray)
289-303 A15 --- name12 *Alternate designation (non-X-ray)
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Note on RA1, DE1, RA2, DE2, RA3, DE3, RA4, and DE4:
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 on flux and e_flux:
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 on name*:
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, Astroph.
Jour. Suppl. 41, 327.
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, Astroph. Jour.
Suppl. 56, 507-649.
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(End) Nancy G. Roman [ADC/SSDOO] May-08-95