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SMCXRAY - SMC X-Ray Discrete Sources



This database contains the 70 `discrete' (i.e., more compact than a few arc minutes) Einstein IPC X-ray sources in the direction of the Small Magellanic Cloud (SMC) that are tabulated in Table 2A of Wang & Wu (1992, ApJS, 78, 391). For full details about the data processing and selection criteria used to create the original source catalog, the above reference should be consulted.

Catalog Bibcode



Wang, Q., and Wu, X. 1992, ApJS, 78, 391.


The name has been constructed with the prefix "SMC" and a numerical designation in the standard IAU fashion based on the 1950 RA and Declination: in this particular case we have truncated to tenths of minutes in time for RA and minutes of angle for Declination. Notice that in the original reference no name was given, only a running number.

The Right Ascension in sexagesimal units.

The Declination in sexagesimal units.

The galactic longitude in degrees.

The galactic latitude in degrees.

Right Ascension in B1950 Coordinates

Declination in B1950 Coordinates

The count rate in counts/s in the IPC broad-band of 0.16 to 3.5 keV.

The count rate error in counts/sec.

The spectral hardness ratio, defined as [CR(hard)-CR(soft)]/CR(broad) where CR(hard) is the count rate in the 0.8 to 3.5 keV band, CR(soft) is the count rate in the 0.16 to 0.8 keV band, and CR(broad) is the count rate in the 0.16 to 3.5 keV band (i.e., the tabulated count rate).

The signal-to-noise ratio.

A source-class identifier code: 1 = supernova remnant 2 = SMC X-ray binary system 3 = OB Association, H II filament, etc. 4 = no identification 5 = foreground galactic star 6 = background AGN (or cluster of galaxies)

A flag to indicate the origin of the source type classification: if set to ":" this indicates that the source type is a `best guess', mainly based on the source's X-ray sepctral characteristics, and thus somewhat uncertain.

Identification Name #1

Identification Name #2

Identification Name #3

A flag that is set to 'Y' if there is a comment in the notes to Table 2 in the original reference that a particular IPC source appears diffuse, i.e., non-pointlike.

Various comments and annotations as well as their references concerning source properties in various wavelength bands. Unless otherwise noted as "SMC", all stellar spectral type designations (e.g., "stars/HD 987") refer to foreground galactic stars. 'V' implies EXOSAT, or multiple IPC, pointings suggesting the source is variable, 'HRI' indicates an observation was also made by the Einstein High Resolution Imager (HRI), and 'P' means that the source appears pointlike in an HRI image.

The numbers in square brackets note references used for information about the X-ray sources and their identifications:

  [1] Seward & Mitchell 1981, ApJ, 243, 736.
  [2] Jones et al. 1985, Space Sci. Rev., 40, 693.
  [3] Mills et al. 1982, MNRAS, 200, 1007.
  [4] Mathewson et al. 1983, ApJS, 51, 345.
  [5] Mathewson et al. 1984, ApJS, 55, 189.
  [6] Bruhweiler et al. 1987, ApJ, 317, 152.
  [7] Inoue, Koyama & Tanaka 1983, in IAU Symp. 101, SNR & Their X-Ray
      Emission, ed. Danziger & Gorenstein, p. 237.
  [8] Pakull 1989, in Recent Developments of Magellanic Cloud Research,
      ed. de Boer et al., p. 183, and references therein.
  [9] Abell et al. 1989, ApJS, 70, 1.
  [N] There is a detailed footnote about the source given in the notes to
      Table 2 in the original reference, Wang & Wu 1992, ApJS, 78, 391.
  [D] The 2 sources so indicated were detected only with the no-aspect data.
Additional information about X-ray source properties, stars, galaxies, OB associations, H II regions, and radio sources was obtained from Henize (1956, ApJS, 2, 315), e.g., N66, Davies et al. (1976, MmRAS, 81, 89), e.g., DEM 32, Mill & Turtle (1984, in IAU Symp. 108, Structure & Evolution of the Magellanic Clouds, ed. van den Bergh & de Boer, p. 283), Hodge (1985, PASP, 97, 530), e.g., H12, the EXOSAT database [the predecessor to the HEASARC database], the EINLINE database, and SIMBAD.

BROWSE classification type. The classification is based on the Source Type parameter.

Contact Person

Questions regarding the SMCXRAY database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Wednesday, 10-Nov-2004 16:03:52 EST