J/ApJ/461/127 The Einstein Two-Sigma Catalog (Moran+ 1996)
The Einstein Two-Sigma Catalog
Moran E.C., Helfand D.J., Becker R.H., White R.L.
<Astrophys. J. 461, 127 (1996)>
=1996ApJ...461..127M 1996ApJ...461..127M
ADC_Keywords: X-ray sources ;
Mission_Name: Einstein
Description:
The X-ray sources from the observations with the Einstein Observatory
(HEAO-2) with intensities of 2-sigma above the background are compiled
in this catalog. This catalog covers more sky at fainter flux levels
than the Einstein Medium Sensitivity Survey. Fields with diffuse
emission sources were excluded. Thus data within 10 degrees of the
galactic plane as well as fields within the boundaries of the
Magellanic Clouds were excluded. The catalog covers 1850 sq. degrees
of the sky.
The generation of the Einstein Two-Sigma Catalog was described in
detail by Moran et al. (1996). Read this article carefully to ensure
responsible use of the Catalog. Address any questions to Ed Moran
(). In particular it should be noted that only 28%,
or about 13,000 sources in the 2-sigma catalog are real sources.
The authors show that cross-correlations with other catalogs is an
effective way to select sources in this catalog that are probably real.
File Summary:
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File Name Lrecl Records Explanations
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ReadMe 80 . This file
twosigma.dat 79 46186 The 2-sigma catalog
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See also:
IX/15 : Einstein Medium Sensitivity Survey Catalog
Byte-by-byte Description of file: twosigma.dat
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Bytes Format Units Label Explanations
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1- 2 I2 h RAh RA (1950) of the source
4- 5 I2 min RAm RA (1950) of the source
7-11 F5.2 s RAs RA (1950) of the source
13 A1 --- DE- Sign Declination (1950)
14-15 I2 deg DEd Dec (1950) of the source
17-18 I2 arcmin DEm Dec (1950) of the source
20-24 F5.2 arcsec DEs Dec (1950) of the source
26-31 F6.2 --- S/N *Signal-to-noise ratio of the source
33-37 I5 --- IPCSEQ IPC Sequence number containing the source
39-45 F7.1 arcmin-2 cnts125 *Number of background-subtracted counts
collected within a 1.25 arcmin radius
circular aperture
47-53 F7.1 arcmin-2 cnts20 *Number of background-subtracted counts
collected within a 2.0 arcmin radius
circular aperture
55-61 F7.1 s exp125 *flatfield-weighted exposure time for the
source in the 1.25 arcmin radius aperture
63-69 F7.1 s exp20 *flatfield-weighted exposure time for the
source in the 2.0 arcmin radius aperture
71-72 I2 --- N125 *Number of "good" pixels used for count in
the 1.25 arcmin radius aperture
74-75 I2 --- N20 *Number of "good" pixels used for count in
the 2.0 arcmin radius aperture
77-79 I3 --- Nbg *Number of "good" pixels used for the background
count in the concentric 3-6 arcmin radius
annulus
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Note on S/N:
Signal-to-noise ratio of the source, based on the counts collected
within a 1.25 arcmin radius circular aperture.
Note on cnts125,cnts20:
The number of background-subtracted counts contained in the source,
collected within circular apertures of radii 1.25 and 2.0 arcmin.
Note on exp125,exp20:
The flatfield-weighted exposure time (sec) for the source in the
1.25 and 2.0 arcmin radius apertures.
Note on N125,N20, Nbg:
The number of ``good'' pixels used to accumulate counts for the
source in the 1.25 arcmin and 2.0 arcmin radius apertures and
for the background in the concentric 3-6 arcmin radius annulus.
The edges of the IPC, its window support ribs, or pixel deletions
resulting from the detection of brighter nearby sources can
cause these numbers to be less than their maximum values of
21, 45, and 304. At least 15 of the 21 pixels in the 1.25 arcmin
aperture had to be unshadowed and undeleted for a source to
to be included in the Catalog.
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References:
Moran, E.C., Helfand, D.J., Becker, R.H., White, R.L. 1996: ApJ. 461, 127.
(End) Paul Kuin (NASA/ADC) 12-Mar-1997