NGC 300 Chandra X-Ray Point Source Catalog

NGC 300 Chandra X-Ray Point Source Catalog NGC300CXO ivo://nasa.heasarc/ngc300cxo NASA/GSFC HEASARC Binder et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the source catalog from a new Chandra ACIS-I observation of the nearby (2.0 Mpc) SA(s)d spiral galaxy NGC 300 which was obtained as part of the Chandra Local Volume Survey (CLVS). This 63-ks exposure covers ~88% of the D25 isophote (R ~ 6.3 kpc) and yields a catalog of 95 X-ray point sources detected at high significance down to a limiting unabsorbed 0.35-8 keV luminosity of ~ 1036 erg/s. Sources were cross-correlated with a previous XMM-Newton catalog, and the authors find 75 "X-ray transient candidate" sources that were detected by one observatory, but not the other. They derive an X-ray scale length of 1.7 +/- 0.2 kpc and a recent star formation rate of 0.12 Msun/yr in excellent agreement with optical observations. Deep, multi-color imaging from the Hubble Space Telescope, covering ~ 32% of this Chandra field, was used to search for optical counterparts to the X-ray sources, and the authors have developed a new source classification scheme to determine which sources are likely X-ray binaries, supernova remnants, and background active galactic nucleus candidates. In the reference paper, the authors present the X-ray luminosity functions (XLFs) at different X-ray energies, and find the total NGC 300 X-ray point-source population to be consistent with other late-type galaxies hosting young stellar populations (<~ 50 Myr). They find that the XLF of sources associated with older stellar populations has a steeper slope than the XLF of X-ray sources coinciding with young stellar populations, consistent with theoretical predictions. NGC 300 was observed on 2010 September 25 for 63 ks using ACIS-I during the Chandra X-Ray Observatory Cycle 12, observation ID 12238. The source detection strategy that was used is described in Section 2.3 of the reference paper. ACIS-Extract (AE) was run a final time on the source list that was produces after an initial run of wavdetect followed by several iterations of AE, and the Poisson probability of not being a source (pns) value was computed in each of the following nine energy bands: 0.5 - 8.0, 0.5 - 2.0, 2.0 - 8.0, 0.5 - 1.0, 1.0 - 2.0, 2.0 - 4.0, 4.0 - 8.0, 0.35 - 1.0 and 0.35 - 8.0 keV. To be included in the final NGC 300 catalog, a source was required to have a pns value less than 4 x 10-6 in any of the nine energy bands; if only the 0.35 - 8 keV band were considered, ~4% of significant sources would have been lost. The final CLVS source catalog for NGC 300 contains 95 sources. This table was initially created by the HEASARC in September 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/758/15/">CDS Catalog J/ApJ/758/15/</a> files table4.dat, table5.dat, table6.dat and table7.dat containing the X-ray properties of the 95 Chandra point sources found in this study. The information on the optical counterparts to (some of) the Chandra X-ray sources and on the X-ray point source classification (presented in Tables 16 and 17, respectively, of the reference paper) is not included herein. It was updated in September 2015 to include the unabsorbed 0.35-8.0 keV energy fluxes (in the parameter herein called b4_flux) from the second reference paper. This is a service provided by NASA HEASARC . 2015AJ....150...94B https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc300cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc300cxo& GET text/xml 180 99999 true 13.698083 -37.807556 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc300cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc300cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc300cxo NGC 300 Chandra X-Ray Point Source Catalog source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable name Source Designation (CXOLV JHHMMSS.ss+DDMMSS.s) 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 Positional Uncertainty arcsec stat.error;pos double nullable b4_counts_limit Limit Flag for 0.35-8 keV Band Net Counts meta.code;phot;em.X-ray char nullable b4_counts 0.35-8 keV Band Net Counts ct phot;em.X-ray double nullable b4_counts_neg_err Lower Uncertainty for 0.35-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b4_counts_pos_err Upper Uncertainty for 0.35-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b4_log_photon_flux Logarithm of 0.35-8 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b4_flux Unabsorbed X-Ray Flux in the 0.35-8 keV Band erg/s/cm^2 phot.flux;em.X-ray 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 b3_counts 2-8 keV Band Net Counts ct phot;em.X-ray double nullable b7_counts_neg_err Lower Uncertainty for 2.6-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b4_log_prob_ns_limit Limit Flag for Logarithm of Band 4 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b3_log_photon_flux Logarithm of 2-8 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b5_log_prob_ns Logarithm of Poisson Probability in 0.35-1.1 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b6_counts 1.1-2.6 keV Band Net Counts ct phot;em.X-ray double nullable b6_counts_limit Limit Flag for 1.1-2.6 keV Band Net Counts meta.code;phot;em.X-ray char nullable b1_log_prob_ns Logarithm of Poisson Probability in 0.5-8 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b6_log_prob_ns Logarithm of Poisson Probability in 1.1-2.6 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b8_counts_limit Limit Flag for 0.35-2 keV Band Net Counts meta.code;phot;em.X-ray char nullable b6_counts_pos_err Upper Uncertainty for 1.1-2.6 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b6_log_prob_ns_limit Limit Flag for Logarithm of Band 6 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable off_axis Off-Axis Angle arcmin instr.offset double nullable b5_counts_pos_err Upper Uncertainty for 0.35-1.1 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b2_counts_limit Limit Flag for 0.5-2 keV Band Net Counts meta.code;phot;em.X-ray char nullable bii Galactic Latitude degree pos.galactic.lat double nullable b1_counts_neg_err Lower Uncertainty for 0.5-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b2_counts_neg_err Lower Uncertainty for 0.5-2 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b7_counts_limit Limit Flag for 2.6-8 keV Band Net Counts meta.code;phot;em.X-ray char nullable b8_counts_neg_err Lower Uncertainty for 0.35-2 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b2_log_prob_ns_limit Limit Flag for Logarithm of Band 2 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b8_counts 0.35-2 keV Band Net Counts ct phot;em.X-ray double nullable b7_counts_pos_err Upper Uncertainty for 2.6-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b7_log_prob_ns_limit Limit Flag for Logarithm of Band 7 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b2_counts_pos_err Upper Uncertainty for 0.5-2 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b8_counts_pos_err Upper Uncertainty for 0.35-2 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b3_counts_neg_err Lower Uncertainty for 2-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b5_counts_limit Limit Flag for 0.35-1.1 keV Band Net Counts meta.code;phot;em.X-ray char nullable b5_log_photon_flux Logarithm of 0.35-1.1 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b3_counts_pos_err Upper Uncertainty for 2-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b6_log_photon_flux Logarithm of 1.1-2.6 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b1_counts_pos_err Upper Uncertainty for 0.5-8 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b2_log_photon_flux Logarithm of 0.5-2 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b4_log_prob_ns Logarithm Poisson Probability in 0.35-8 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b1_counts 0.5-8 keV Band Net Counts ct phot;em.X-ray double nullable b1_log_prob_ns_limit Limit Flag for Logarithm of Band 1 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b7_log_photon_flux Logarithm of 2.6-8 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable extraction_radius Average Radius of Source Extraction Region pixel phys.angSize;instr.det double nullable b7_log_prob_ns Logarithm of Poisson Probability in 2.6-8 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b3_log_prob_ns_limit Limit Flag for Logarithm of Band 3 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b6_counts_neg_err Lower Uncertainty for 1.1-2.6 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b5_counts 0.35-1.1 keV Band Net Counts ct phot;em.X-ray double nullable b3_counts_limit Limit Flag for 2-8 keV Band Net Counts meta.code;phot;em.X-ray char nullable b5_log_prob_ns_limit Limit Flag for Logarithm of Band 5 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b1_counts_limit Limit Flag for 0.5-8 keV Band Net Counts meta.code;phot;em.X-ray char nullable mean_expo_map_value Sum of Mean Exposure Map Value in Source Region s.cm^2 meta.number;obs.exposure double nullable b8_log_prob_ns Logarithm of Poisson Probability in 0.35-2 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable b8_log_prob_ns_limit Limit Flag for Logarithm of Band 8 Poisson Probability meta.code;stat.probability;src;em.X-ray char nullable b5_counts_neg_err Lower Uncertainty for 0.35-1.1 keV Band Net Counts ct stat.error;phot;em.X-ray double nullable b3_log_prob_ns Logarithm of Poisson Probability in 2-8 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b7_counts 2.6-8 keV Band Net Counts ct phot;em.X-ray double nullable b8_log_photon_flux Logarithm of 0.35-2 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable b2_log_prob_ns Logarithm of Poisson Probability in 0.5-2 keV Band Is Not a Source stat.probability;src;em.X-ray double nullable b2_counts 0.5-2 keV Band Net Counts ct phot;em.X-ray double nullable b1_log_photon_flux Logarithm of 0.5-8 keV Band Photon Flux log(ct/cm^2/s) phot.flux;em.X-ray double nullable