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TRIFIDCXO - Trifid Nebula (M 20) Chandra X-Ray Point Source Catalog



This table contains a list of the Trifid Nebula (M 20) X-Ray point sources detected by the Chandra X-ray Observatory (CXO) in an observation carried out on 2002 June 13. The Trifid Nebula, a young star-forming H II region, was observed for 16 hr by the Advanced CCD Imaging Spectrometer imaging array, ACIS-I, detector. 304 X-ray sources were detected, 30% of which are hard sources (defined as those sources having a 0.5-2.0 keV to 2.0-8.0 keV hardness ratio > -0.2) and 70% of which have near-infrared counterparts.

Catalog Bibcode



Chandra observation of the Trifid nebula: X-ray emission from the O star
complex and actively forming pre-main-sequence stars.
    Rho J., Ramirez S.V., Corcoran M.F., Hamaguchi K., Lefloch B.
   <Astrophys. J., 607, 904-912 (2004)>


This table was created by the HEASARC in January 2007 based on CDS table J/ApJ/607/904/table1.dat.


The X-ray source name using the prefix 'CXOM20 J' for Chandra X-ray Observatory, the target (M 20), and the J2000 equatorial coordinates of the source.

An alternative name for the X-ray source, using the prefix 'RRC2004 ' (Rho, Ramirez, Corcoran 2004) and the source number of the X-ray source.

An X-ray source number in order of increasing J2000 Right Ascension.

The preliminary source identification number derived from the wavelet analysis tool (wavdetect). This was run using an exposure map and it produced a catalog of 354 sources from the entire ACIS-I 17' by 17' field of view (FOV). The authors then identified spurious sources due to cosmic rays or to cases where the source counts were less than the background counts, and rejected 50 of these sources, leading to their final catalog of 304 sources contained in the present table.

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.

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.

The Galactic Longitude of the X-ray source.

The Galactic Latitude of the X-ray source.

The net count rate in the 0.5-8.0 keV band of the X-ray source, in counts per second, derived from the wavelet analysis.

The uncertainty in the X-ray source count rate, in counts per second.

The signal-to-noise ratio of the X-ray source detection.

The X-ray source spectral hardness ratio HR between the counts in the soft (0.5-2.0) keV and hard (2.0-8.0 keV) energy bands, S and H, respectively, defined by the relation HR =(H-S)/(H+S).

The uncertainty in the X-ray spectral hardness ratio, HR.

Contact Person

Questions regarding the TRIFIDCXO database table can be addressed to the HEASARC User Hotline.
Page Author: Browse Software Development Team
Last Modified: Tuesday, 09-Jan-2007 13:09:59 EST