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CENACXO - Centaurus A Galaxy Chandra X-Ray Point Source Catalog

HEASARC
Archive

Overview

This table contains the results from two Chandra X-ray Observatory observations of the X-ray point source population in the nearby radio galaxy Centaurus A (NGC 5128). Using a wavelet decomposition detection algorithm, 246 individual point sources are detected above a limiting luminosity of ~ 2 * 10^36 ergs/s, 82 of which are detected in both data sets where the fields of view overlap. Thirty-eight sources were detected in only one observation but were within the field of view of both pointings, implying considerable variability. Eight foreground stars were identified in these observations, and nine of the sources were identified with known globular clusters in Centaurus A. All previously observed ROSAT sources within our field of view were detected. The faintest source in this table has 5 counts, which corresponds to a limiting luminosity of ~2.2 x 10^36 erg/s at the center of the field of view.

The two observations of Cen A were made with the ACIS-I array (observation IDs were 00316 and 00962) on 1999 December 5 and 2000 May 17, with 35.9 36.5 ks exposures, respectively.


Catalog Bibcode

2001ApJ...560..675K

References

Chandra observations of the X-ray point source population in Centaurus A.
    Kraft R.P., Kregenow J.M., Forman W.R., Jones C., Murray S.S.
   <Astrophys. J. 560, 675 (2001)>
   =2001ApJ...560..675K

Provenance

This table was created by the HEASARC in February 2007 based on CDS table J/ApJ/560/675 file table2.dat.

HEASARC Implementation

The HEASARC has created a parameter called source_number which reflects the order in which the sources were listed in Table 2 of the reference paper, i.e., in order of increasing J2000.0 Right Ascension.

Parameters

Source_Number
A running X-ray source number in order of increasing J2000.0 Right Ascension created by the HEASARC (see HEASARC_Implementation above).

Name
The preferred designation for the X-ray source using the '[KKF2001]' prefix (for Kraft, Kregenow and Forman 2001) and the J2000.0 coordinates (JHHMMSS.ss-DDMMSS.ss), as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

Alt_Name
An alternative designation for the X-ray source using the '[KKF2001]' prefix (for Kraft, Kregenow and Forman 2001) and the value of the source number parameter, as recommended by the CDS Dictionary of Nomenclature of Celestial Objects.

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 seconds of time in the original table. The X-ray positions were placed in the USNO-A2.0 reference frame by matching the positions of 6 X-ray sources with their USNO counterpart positions: this required a small (~1") adjustment to the original X-ray positions. The authors estimate that the rms error in the absolute positions is ~0.5".

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000.0 coordinates to a precision of 0.01 arcseconds in the original table. The X-ray positions were placed in the USNO-A2.0 reference frame by matching the positions of 6 X-ray sources with their USNO counterpart positions: this required a small (~1") adjustment to the original X-ray positions. The authors estimate that the rms error in the absolute positions is ~0.5".

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Lx_1_Limit
This parameter is set to '<' to indicate that the source was seen in the other observation but not seen in this one, although it was within the FOV. Thus, the reported luminosity for this observation is an upper limit based on the size of a 3-sigma fluctuation in the background.

Lx_1
The 0.4 - 10 keV luminosity, in erg/s, of the X-ray source in the first Chandra observation (ObsID = 316 made on 5 Dec 1999). The source count rates were converted to source X-ray luminosities assuming a distance of 3.5 Mpc to Cen A, and a 5 keV bremsstrahlung spectrum with Galactic absorption (7 x 10^20 H atoms cm^-2). The conversion between count rate in the 0.5 - 4.5 keV band and absorbed flux in the 0.4 - 10 keV band is 10^-3 ct/s = 9.8 x 10^-15 erg/cm^2/s. The unabsorbed flux in the 0.4 - 10 keV band is 9% larger.

Lx_2_Limit
This parameter is set to '<' to indicate that the source was seen in the other observation but not seen in this one, although it was within the FOV. Thus, the reported luminosity for this observation is an upper limit based on the size of a 3-sigma fluctuation in the background.

Lx_2
The 0.4 - 10 keV luminosity, in erg/s, of the X-ray source in the second Chandra observation (ObsID = 962 made on 17 May 2000). The source count rates were converted to source X-ray luminosities assuming a distance of 3.5 Mpc to Cen A, and a 5 keV bremsstrahlung spectrum with Galactic absorption (7 x 10^20 H atoms cm^-2). The conversion between count rate in the 0.5 - 4.5 keV band and absorbed flux in the 0.4 - 10 keV band is 10^-3 ct/s = 9.8 x 10^-15 erg/cm^2/s. The unabsorbed flux in the 0.4 - 10 keV band is 9% larger.

Note_Flags
This parameter contains codes which indicate various notes concerning the observation or the identification of the source, using the following conventions:

      fgs = foreground stars from the USNO A2.0 (CDS Cat. <I/252> catalog;
       GC = globular clusters (Harris et al. 1984ApJ...287..175H and
            Minitti et al. 1996ApJ...467..221M, [MAG95] NN in Simbad);
      PNN = previously observed by the ROSAT PSPC detector
            (Turner et al., 1997ApJ...475..118T, [TGM97] PNN in Simbad);
      HNN = previously observed by the ROSAT HRI detector
            (Turner et al., 1997ApJ...475..118T, [TGM97] HNN);
      SSS = super-soft source;
      stv = short-term variable, defined as variable within one of the
            observations (see text of paper for a complete discussion of
            the criteria for variability);
      ltv = long-term variable, defined as variable between the two observations
            (see text of paper for a complete discussion of the criteria for
            variability).
  

Contact Person

Questions regarding the CENACXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 26-Feb-2007