NGC 4649 Chandra X-Ray Point Source Catalog 2

NGC 4649 Chandra X-Ray Point Source Catalog 2 NGC4649CX2 ivo://nasa.heasarc/ngc4649cx2 NASA/GSFC HEASARC Luo et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the main X-ray source catalog for the Chandra monitoring observations of the 16.5-Mpc distant elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501 X-ray sources detected in the 0.3-8.0 keV band in the merged observation or in one of the six individual observations; 399 sources are located within the D25 ellipse. The observed 0.3-8.0 keV luminosities of these 501 sources range from 9.3 x 1036 erg s-1 to 5.4 x 1039 erg s-1. The 90% detection completeness limit within the D25 ellipse is 5.5 x 1037 erg s-1. Based on the surface density of background active galactic nuclei (AGNs) and the detection completeness, we expect ~ 45 background AGNs among the catalog sources (~ 15 within the D25 ellipse). There are nine sources with luminosities greater than 1039 erg s-1, which are candidates for ultraluminous X-ray sources. The nuclear source of NGC 4649 is a low-luminosity AGN, with an intrinsic 2.0-8.0 keV X-ray luminosity of 1.5 x 1038 erg s-1. The X-ray colors suggest that the majority of the catalog sources are low-mass X-ray binaries (LMXBs). The authors find that 164 of the 501 X-ray sources show long-term variability, indicating that they are accreting compact objects, and discover four transient candidates and another four potential transients. They also identify 173 X-ray sources (141 within the D25 ellipse) that are associated with globular clusters (GCs) based on Hubble Space Telescope and ground-based data; these LMXBs tend to be hosted by red GCs. Although NGC 4649 has a much larger population of X-ray sources than the structurally similar early-type galaxies, NGC 3379 and NGC 4278, the X-ray source properties are comparable in all three systems. This HEASARC table contains the main Chandra source catalog of the basic properties of the 501 X-ray detected sources (Table 3 in the reference paper which includes both sources detected in the merged X-ray image as well as a number only detected in the individual observations), and also the information on source counts, hardness ratios and soft and hard X-ray colors in the merged observation for the same 501 X-ray detected sources (Table 4 in the reference paper). It does not contain the information on source counts, hardness ratios and soft and hard X-ray colors for these same sources in the six individual observations that were contained in Tables 5 - 10 of the reference paper. This table was created by the HEASARC in March 2013 based on the electronic version of Tables 3 and 4 from the reference paper which were obtained from the ApJS website.. This is a service provided by NASA HEASARC . 2013ApJS..204...14L https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc4649cx2.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc4649cx2& GET text/xml 180 99999 true 190.8935 11.4425 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc4649cx2 GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc4649cx2&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc4649cx2 NGC 4649 Chandra X-Ray Point Source Catalog 2 source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable name IAU-Style Source Designation 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 log_lx_limit 3-Sigma Upper Limit on the Logarithm of 0.3-8 keV X-Ray Luminosity meta.code;phys.luminosity;em.X-ray char nullable log_lx Logarithm of 0.3-8 keV X-Ray Luminosity (in erg/s) log(erg/s) phys.luminosity;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable counts_limit Limit Flag for Net 0.3-8 keV Counts meta.code;phot;em.X-ray char nullable sb2_counts_pos_err Upper 1-Sigma Uncertainty in Net 1-2 keV Counts ct stat.error;phot;em.X-ray.soft double nullable hard_color_pos_err Upper 1-Sigma Uncertainty in Hard X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable radial_distance Radial Distance of Source from Nucleus arcmin pos.angDistance double nullable sb_counts Net 0.3-2 keV Counts ct phot;em.X-ray.soft double nullable variability_flag Flag Indicates Variability meta.code;src.var char nullable hardness_ratio_neg_err Lower 1-Sigma Uncertainty in Hardness Ratio stat.error;phot;arith.ratio;em.X-ray double nullable sb1_counts_neg_err Lower 1-Sigma Uncertainty in Net 0.3-1 keV Counts ct stat.error;phot;em.X-ray.soft double nullable hardness_ratio_pos_err Upper 1-Sigma Uncertainty in Hardness Ratio stat.error;phot;arith.ratio;em.X-ray double nullable hb_counts_neg_err Lower 1-Sigma Uncertainty in Net 2-8 keV Counts ct stat.error;phot;em.X-ray.medium double nullable hb_counts Net 2-8 keV Counts ct phot;em.X-ray.medium double nullable bii Galactic Latitude degree pos.galactic.lat double nullable counts Net 0.3-8 keV Counts ct phot;em.X-ray double nullable hb_counts_limit Limit Flag for Net 2-8 keV Counts meta.code;phot;em.X-ray.medium char nullable sb2_counts Net 1-2 keV Counts ct phot;em.X-ray.soft double nullable counts_neg_err Lower 1-Sigma Uncertainty in Net 0.3-8 keV Counts ct stat.error;phot;em.X-ray double nullable sb1_counts Net 0.3-1 keV Counts ct phot;em.X-ray.soft double nullable hard_color Hard X-Ray Color: (HB-SB2)/FB phot;arith.ratio;em.X-ray double nullable hardness_ratio Hardness Ratio: (HB-SB)/(HB+SB) phot.flux;arith.ratio;em.X-ray double nullable soft_color_neg_err Lower 1-Sigma Uncertainty in Soft X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable hard_color_neg_err Lower 1-Sigma Uncertainty in Hard X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable sb1_counts_limit Limit Flag for Net 0.3-1 keV Counts meta.code;phot;em.X-ray.soft char nullable sb2_counts_limit Limit Flag for Net 1-2 keV Counts meta.code;phot;em.X-ray.soft char nullable sb_counts_neg_err Lower 1-Sigma Uncertainty in Net 0.3-2 keV Counts ct stat.error;phot;em.X-ray.soft double nullable soft_color_pos_err Upper 1-Sigma Uncertainty in Soft X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable variability_significance Maximum Statistical Significance for Variability stat.likelihood;src.var;em.X-ray double nullable counts_pos_err Upper 1-Sigma Uncertainty in Net 0.3-8 keV Counts ct stat.error;phot;em.X-ray double nullable sb2_counts_neg_err Lower 1-Sigma Uncertainty in Net 1-2 keV Counts ct stat.error;phot;em.X-ray.soft double nullable sb_counts_limit Limit Flag for Net 0.3-2 keV Counts meta.code;phot;em.X-ray.soft char nullable gc_identifier GC Identifier meta.id.cross char nullable soft_color Soft X-Ray Color: (SB2-SB1)/FB phot;arith.ratio;em.X-ray double nullable hb_counts_pos_err Upper 1-Sigma Uncertainty in Net 2-8 keV Counts ct stat.error;phot;em.X-ray.medium double nullable sb_counts_pos_err Upper 1-Sigma Uncertainty in Net 0.3-2 keV Counts ct stat.error;phot;em.X-ray.soft double nullable positional_flag Positional Flag meta.code short nullable sb1_counts_pos_err Upper 1-Sigma Uncertainty in Net 0.3-1 keV Counts ct stat.error;phot;em.X-ray.soft double nullable opt_ctrpart_flag Flag [0-9] Indicates Optical Association Note meta.code;src;em.opt short 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