ONCCXOXRAY ivo://nasa.heasarc/onccxoxray NASA/GSFC HEASARC Flaccomio et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source In the first of two companion papers on the Orion Nebula Cluster (ONC), the authors presented their analysis of a 63 ks Chandra HRC-I observation that yielded 742 X-ray detections within the 30' x 30' field of view. To facilitate their interpretation of the X-ray image, they compiled a multi-wavelength catalog of nearly 2900 known objects in the region by combining 17 different catalogs from the recent literature. They defined two reference groups: an infrared sample, containing all objects detected in the K band, and an optical sample comprising low-extinction, well-characterized ONC members. They showed for both samples that field object contamination is generally low. Their X-ray sources are primarily low-mass ONC members. The detection rate for optical sample stars increases monotonically with stellar mass from zero at the brown dwarf limit to ~100% for the most massive stars but shows a pronounced dip between 2 and 10 M<sub>sun</sub>. They determined L<sub>X</sub> and L<sub>X</sub>/L<sub>bol</sub> or all stars in their optical sample and utilized this information in their companion paper to study correlations between X-ray activity and other stellar parameters. In particular, the authors assembled an extensive catalog of known X-ray/optical/IR and radio objects that fell within the HRC FOV. In addition to their list of HRC sources and the Chandra source lists of Garmire et al. (2000, <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/AJ/120/1426">CDS Cat. <J/AJ/120/1426></a>) and Schulz et al. (2001, CDS Cat. <J/ApJ/549/441>), they considered 14 catalogs from recent publications, producing a database of nearly 2900 distinct objects reported in at least one of the studies considered. A full list of references is given in the first column of Table 2 of the reference paper, along with a concise classification of the work and the referenced table number(s) from the original work. The HRC on board the Chandra X-Ray Observatory (Weisskopf et al., 2002PASP..114....1W) observed the ONC for 63.2ks on 2000 February 4. The pointing (R.A. = 5h 35m 17s, DE=-5{deg} 23' 16" (J2000.0)) was chosen to place the Trapezium region and the bright O star Theta<sup>1</sup> Ori C in the center of the field of view (FOV). A good fraction of the ONC region was included in the 30' x 30' HRC FOV. This HEASARC table lists the properties of the 742 X-ray sources detected in this observation as presented in the full version of Table 1 of the reference paper. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJ/582/382, file table1.dat. This is a service provided by NASA HEASARC . 2003ApJ...582..382F https://heasarc.gsfc.nasa.gov/W3Browse/all/onccxoxray.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=onccxoxray& GET text/xml 180 99999 true 83.93204167 -5.68124444 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=onccxoxray GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_onccxoxray&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public onccxoxray Orion Nebula Cluster Chandra HRC X-Ray Point Source Catalog name Catalog Source Designation ([FDM2003] X NNN in SIMBAD) meta.id;meta.main char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable error_radius Statistical Uncertainty in Position (arcsec) arcsec stat.error;pos double nullable counts X-Ray Counts ct phot;em.X-ray double nullable counts_error Uncertainty in X-Ray Counts ct stat.error;phot;em.X-ray double nullable snr Detection Signal-to-Noise Ratio stat.snr double nullable bii Galactic Latitude degree pos.galactic.lat double nullable exposure Effective Exposure Time (s) s time.duration;obs.exposure double nullable source_number Sequential Identification Number for Each X-Ray Source in Catalog meta.id short nullable lii Galactic Longitude degree pos.galactic.lon double nullable "__x_ra_dec" System unit vector column double nullable "__y_ra_dec" System unit vector column double nullable "__z_ra_dec" System unit vector column double nullable "__row" System index column char nullable