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NGC2516CXO - NGC 2516 Chandra X-Ray Point Source Catalog

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Overview

The NGC 2516 Chandra X-Ray Point Source Catalog is the result of a comprehensive study of the Chandra X-ray observations of the young open star cluster NGC 2516. The authors have analyzed eight individual Chandra observations, comprising 5 ACIS and 3 HRC-I observations. They have combined these datasets to achieve the greatest sensitivity, reaching down to a threshold level of log f_X = -14.56 (erg/s/cm^2), or log L_X = 28.69 (erg/s) at the 387 pc distance of NGC 2516. Out of 284 X-ray sources detected, 155 are identified with photometric cluster members, with very little ambiguity, another 60 with non-members. There are 4 X-ray sources with two possible optical identifications (one cluster member and one nonmember for each), with no obvious choice between the two candidates. These 4 X-ray sources are listed in this Browse table twice, one for each optical counterpart, hence there are (284 + 4 =) 288 entries. There remain 73 X-ray sources without an optical identification with the authors' optical catalog stars.

Catalog Bibcode

2003ApJ...588.1009D

References

Chandra X-ray observations of the young open cluster NGC 2516.
    Damiani F., Flaccomio E., Micela G., Sciortino S., Harnden F.R.Jr,
    Murray S.S., Wolk S.J., Jeffries R.D.
   <Astrophys. J. 588, 1009 (2003)>
   =2003ApJ...588.1009D

Provenance

This Browse table was created by the HEASARC in December 2006, based on CDS table J/ApJ/588/1009, files table4.dat and table5.dat.

Parameters

Source_Number
A running sequential identification number in order of increasing J2000 Right Ascension. This was used by the HEASARC to construct a name for the X-ray source, using the prefix '[DFM2003] ' recommended by the Dictionary of Nomenclature of Celestial Objects.

Name
The name of the X-ray source constructed using the prefix '[DFM2003] ' recommended by the Dictionary of Nomenclature of Celestial Objects and the running sequential identification number (source_number).

RA
The Right Ascension of the X-ray source in the selected equinox. This was given in J2000 coordinates to a precision of 0.01 seconds of time in the originating table. It is a weighted average of the individual positions for sources detected more than once, using the inverse square of the error as the weight. The quoted value includes a systematic correction of 0.07" based on matching the X-ray and Jeffries et al. (2001A&A...375..863J) optical positions.

Dec
The Declination of the X-ray source in the selected equinox. This was given in J2000 coordinates to a precision of 0.1 arcseconds in the originating table. It is a weighted average of the individual positions for sources detected more than once, using the inverse square of the error as the weight. The quoted value includes a systematic correction of 0.19" based on matching the X-ray and Jeffries et al. (2001A&A...375..863J) optical positions.

LII
The Galactic Longitude of the X-ray source.

BII
The Galactic Latitude of the X-ray source.

Error_Radius
The positional error of the X-ray source, in arcseconds.

Photon_Flux
The mean photon flux (or count rate per effective area) of the X-ray source, in counts/s/cm^2. It is a weighted average of the individual fluxes for sources detected more than once, using the inverse square of the error as the weight. More complete details of how the mean fluxes were calculated are given in Section 3.3 of the published paper.

Photon_Flux_Error
The uncertainty in the mean photon flux, in cts/s/cm^2.

Number_Detections
The number of Chandra observations in which the X-ray source was detected.

Jth_Number
The Jeffries et al. (2001A&A...375..863J) or JTH Number, NNNNN, of the optical counterpart to the X-ray source. JTH stars are denominated as `Cl* NGC 2516 JTH NNNNN' in the Simbad database. More complete details of how the X-ray sources and stars were matched are given in Section 4 of the published paper.

Offset
The offset between the X-ray source and the optical counterpart, in arcseconds.

Vmag
The V Band magnitude of the optical counterpart to the X-ray source, from the optical catalog of Jeffries et al. (2001A&A...375..863J), complete to about V = 20, supplemented by a list of brighter stars, as reoprted by Jeffries et al. (1997MNRAS.287..350J).

BV_Color
The (B-V) color of the optical counterpart to the X-ray source, from the optical catalog of Jeffries et al. (2001A&A...375..863J), complete to about V = 20, supplemented by a list of brighter stars, as reoprted by Jeffries et al. (1997MNRAS.287..350J).

VI_Color
The (V-I) color of the optical counterpart to the X-ray source, from the optical catalog of Jeffries et al. (2001A&A...375..863J), complete to about V = 20, supplemented by a list of brighter stars, as reoprted by Jeffries et al. (1997MNRAS.287..350J).

Cluster_Flag
This parameter flags whether ('Y') or not ('N') the optical counterpart to the X-ray source is a member of the NGC 2516 cluster.

Binary_Flag
This parameter flags whether ('Y') or not ('N') the optical counterpart to the X-ray source is a known binary system.

Log_Lx
The log of the X-ray luminosity of the X-ray source in the 0.1 - 4 keV band, provided that it is a cluster member, in erg/s. (X-ray luminosities are not provided for the 60 X-ray sources associated with nonmembers). A distance of 387 pc and an absorption column density of 8.2 x 10^20 cm^-2 (Jeffries et al. 2001A&A...375..863J), corresponding to the cluster extinction A_V = 0.372, has been assumed for NGC 2516. The methodology used to convert the count rates into X-ray fluxes is discussed in detail in Section 3.4 of the published paper.


Contact Person

Questions regarding the NGC2516CXO database table can be addressed to the HEASARC User Hotline.

Page Author: Browse Software Development Team
Last Modified: 12-Dec-2006