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
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:
FileName Lrecl Records Explanations
ReadMe 80 . This file twosigma.dat 79 46186 The 2-sigma catalog
See also: IX/15 : Einstein Medium Sensitivity Survey Catalog Byte-by-byte Description of file: twosigma.dat
Bytes Format Units Label Explanations
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
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.
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
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