NGC 1291 Chandra X-Ray Point Source Catalog NGC1291CXO ivo://nasa.heasarc/ngc1291cxo 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 some of the results from a study of the X-ray binary (XRB) populations in the bulge and ring regions of the ring galaxy NGC 1291. Utilizing the four available Chandra observations totaling an effective exposure of 179 ks, the authors detect 169 X-ray point sources in the galaxy in the full band (0.3 - 8.0 keV) with a false-positive probability threshold of 10<sup>-6</sup> (implying approximately 2 false detections given the size of the image). Of these sources, 75 are in the bulge and 71 are in the ring. The authors report photometric properties of these sources in a point-source catalog. There are ~ 40% of the bulge sources and ~ 25% of the ring sources showing > 3-sigma long-term variability in their X-ray count rate. The X-ray colors suggest that a significant fraction of the bulge (~ 75%) and ring (~ 65%) sources are likely low-mass X-ray binaries (LMXBs). The spectra of the nuclear source indicate that it is a low-luminosity active galactic nucleus (AGN) with moderate obscuration; spectral variability is observed between individual observations. The authors construct 0.3-8.0 keV X-ray luminosity functions (XLFs) for the bulge and ring XRB populations, taking into account the detection incompleteness and background AGN contamination. They reach 90% completeness limits of ~ 1.5 x 10<sup>37</sup> and ~ 2.2 x 10<sup>37</sup> erg s<sup>-1</sup> for the bulge and ring populations, respectively. Both XLFs can be fit with a broken power-law model, and the shapes are consistent with those expected for populations dominated by LMXBs. In the paper, the authors perform detailed population synthesis modeling of the XRB populations in NGC 1291, which suggests that the observed combined XLF is dominated by an old LMXB population. They compare the bulge and ring XRB populations, and argue that the ring XRBs are associated with a younger stellar population than the bulge sources, based on the relative overdensity of X-ray sources in the ring, the generally harder X-ray color of the ring sources, the overabundance of luminous sources in the combined XLF, and the flatter shape of the ring XLF. This table was created by the HEASARC in May 2012 based on an electronic version of Table 2 from the reference paper obtained from the ApJ website. This is a service provided by NASA HEASARC . 2012ApJ...749..130L https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc1291cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc1291cxo& GET text/xml 180 99999 true 49.34795833 -41.21744444 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc1291cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc1291cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc1291cxo NGC 1291 Chandra X-Ray Point Source Catalog name 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 off_axis Off-Axis Angle of X-Ray Source arcmin instr.offset double nullable radial_distance Radial Distance of X-Ray Source to Galaxy Nucleus arcmin pos.angDistance double nullable fb_counts Full (0.3-8.0 keV) Band Source Counts ct phot;em.X-ray double nullable fb_counts_pos_err Upper 1-Sigma Error in Full Band Source Counts ct stat.error;phot;em.X-ray double nullable fb_counts_neg_err Lower 1-Sigma Error in Full Band Source Counts ct stat.error;phot;em.X-ray double nullable lx Observed Full-Band X-Ray Luminosity (erg/s) erg/s phys.luminosity;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 photon_index Photon Index spect.index double nullable hard_color_pos_err Upper 1-Sigma Error in Hard Color stat.error;phot.count;arith.ratio;em.X-ray double nullable csb_counts_neg_err Lower 1-Sigma Error in Conventional Soft Band Source Counts ct stat.error;phot;em.X-ray.soft double nullable soft_color_pos_err Upper 1-Sigma Error in Soft Color stat.error;phot.count;arith.ratio;em.X-ray double nullable hard_color Hard Color: (H-M)/T phot.count;arith.ratio;em.X-ray double nullable hb_counts_neg_err Lower 1-Sigma Error in Hard Band Source Counts ct stat.error;phot;em.X-ray.medium double nullable sb_counts_limit Limit Flag for Soft Band Source Counts meta.code;phot;em.X-ray.soft char nullable exposure Full Band Effective Exposure Time s time.duration;obs.exposure double nullable hb_counts Hard (2.0-8.0 keV) Band Source Counts ct phot;em.X-ray.medium double nullable csb_counts Conventional Soft (0.5-2.0 keV) Band Source Counts ct phot;em.X-ray.soft double nullable var_significance Full-Band Flux Variability Statistical Significance meta.code;src.var double nullable csb_counts_limit Limit Flag for Conventional Soft Band Source Counts meta.code;phot;em.X-ray.soft char nullable hb_counts_pos_err Upper 1-Sigma Error in Hard Band Source Counts ct stat.error;phot;em.X-ray.medium double nullable sb2_counts_neg_err Lower 1-Sigma Error in Soft Band #2 Source Counts ct stat.error;phot;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable hb_counts_limit Limit Flag for Hard Band Source Counts meta.code;phot;em.X-ray.medium char nullable csb_counts_pos_err Upper 1-Sigma Error in Conventional Soft Band Source Counts ct stat.error;phot;em.X-ray.soft double nullable sb_counts Soft (0.3-2.0 keV) Band Source Counts ct phot;em.X-ray.soft double nullable sb1_counts_neg_err Lower 1-Sigma Error in Soft Band #1 Source Counts ct stat.error;phot;em.X-ray.soft double nullable sb_counts_pos_err Upper 1-Sigma Error in Soft Band Source Counts ct stat.error;phot;em.X-ray.soft double nullable sb_counts_neg_err Lower 1-Sigma Error in Soft Band Source Counts ct stat.error;phot;em.X-ray.soft double nullable sb1_counts_pos_err Upper 1-Sigma Error in Soft Band #1 Source Counts ct stat.error;phot;em.X-ray.soft double nullable soft_color_neg_err Lower 1-Sigma Error in Soft Color stat.error;phot.count;arith.ratio;em.X-ray double nullable sb1_counts Soft (0.3-1.0 keV) Band #1 Source Counts ct phot;em.X-ray.soft double nullable sb2_counts_pos_err Upper 1-Sigma Error in Soft Band #2 Source Counts ct stat.error;phot;em.X-ray.soft double nullable soft_color Soft Color: (M-S)/T phot.count;arith.ratio;em.X-ray double nullable bii Galactic Latitude degree pos.galactic.lat double nullable alt_name Alternative Catalog-Based Source Designation meta.id char nullable sb2_counts_limit Limit Flag for Soft Band #2 Source Counts meta.code;phot;em.X-ray.soft char nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable sb1_counts_limit Limit Flag for Soft Band #1 Source Counts meta.code;phot;em.X-ray.soft char nullable region_flag Value Indicates Region Where Source Is Located: Bulge, Ring, or Other meta.code;src.morph char nullable hard_color_neg_err Lower 1-Sigma Error in Hard Color stat.error;phot.count;arith.ratio;em.X-ray double nullable sb2_counts Soft (1.0-2.0 keV) Band #2 Source Counts ct phot;em.X-ray.soft double nullable