NuSTAR Hard X-Ray Survey of the Galactic Center NUGALCEN ivo://nasa.heasarc/nugalcen NASA/GSFC HEASARC Hong 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 the first survey results of hard X-ray point sources in the Galactic Center (GC) region obtained by NuSTAR. The authors have discovered 70 hard (3-79 keV) X-ray point sources in a 0.6 deg&lt;sup&gt;2&lt;/sup&gt; region around Sgr A* with a total exposure of 1.7 Ms, and 7 sources in the Sgr B2 field with 300 ks. They identify clear Chandra counterparts for 58 NuSTAR sources and assign candidate counterparts for the remaining 19. The NuSTAR survey reaches X-ray luminosities of ~4 x 10&lt;sup&gt;32&lt;/sup&gt; and ~8 x 10&lt;sup&gt;32&lt;/sup&gt; erg/s at the GC (8 kpc) in the 3-10 and 10-40 keV bands, respectively. The source list includes three persistent luminous X-ray binaries (XBs) and the likely run-away pulsar called the Cannonball. New source-detection significance maps reveal a cluster of hard (&gt;10 keV) X-ray sources near the Sgr A diffuse complex with no clear soft X-ray counterparts. The severe extinction observed in the Chandra spectra indicates that all the NuSTAR sources are in the central bulge or are of extragalactic origin. Spectral analysis of relatively bright NuSTAR sources suggests that magnetic cataclysmic variables constitute a large fraction (&gt;40% - 60%). Both spectral analysis and logN - logS distributions of the NuSTAR sources indicate that the X-ray spectra of the NuSTAR sources should have kT &gt; 20 keV on average for a single-temperature thermal plasma model or an average photon index of Gamma = 1.5 - 2 for a power-law model. These findings suggest that the GC X-ray source population may contain a larger fraction of XBs with high plasma temperatures than the field population. The observations of the GC region with NuSTAR began in 2012 July, shortly after its launch. The original survey strategy for the GC region was to match the central 2 degree x 0.7 degree region covered by the Chandra X-ray Observatory (Wang et al. 2002, Nature, 415, 148; Muno et al. 2009, ApJS, 181, 110). The field of views (FOVs) of neighboring NuSTAR observations in the survey were designed to overlap with each other by ~40%. Multiple observations of the same region with relatively large FOV offsets tend to average out the vignetting effects of each observation, enabling a more uniform coverage of the region. Multiple observations are also suitable for monitoring long term X-ray variability of sources in the region. Even when observing a single target, the NuSTAR observation is often broken up into two or more segments with relatively large pointing offsets to allow an efficient subtraction of a detector coordinate-dependent background component (e.g., Mori et al. 2013, ApJ, 770, L23). This table was created by the HEASARC in March 2018, based on &lt;a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/825/132"&gt;CDS Catalog J/ApJ/825/132&lt;/a&gt; files table2.dat, table3.dat, table4.dat and table5.dat. This is a service provided by NASA HEASARC . 2016ApJ...825..132H https://heasarc.gsfc.nasa.gov/W3Browse/all/nugalcen.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=nugalcen& GET text/xml 180 99999 true 265.85717 -29.5625 0.0333333333333333 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=nugalcen GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_nugalcen&Action=More+Options&Action=Parameter+Search&ConeAdd=1 NUSTAR 0.0333333333333333 X-ray public nugalcen NuSTAR Hard X-Ray Survey of the Galactic Center 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 counts Net Counts in the 3-40 keV Band ct phot;em.X-ray int nullable counts_error Uncertainty in Net Counts in the 3-40 keV Band ct stat.error;phot;em.X-ray short nullable sb_lx The Observed NuSTAR 3-10 keV Luminosity at 8 kpc erg/s phys.luminosity;em.X-ray.medium double nullable sb_lx_error Uncertainty in the Observed NuSTAR 3-10 keV Luminosity at 8 kpc erg/s stat.error;phys.luminosity;em.X-ray.medium double nullable hb_lx The Observed NuSTAR 10-40 keV Luminosity at 8 kpc erg/s phys.luminosity;em.X-ray.hard double nullable hb_lx_error Uncertainty in the Observed NuSTAR 10-40 keV Luminosity at 8 kpc erg/s stat.error;phys.luminosity;em.X-ray.hard double nullable hb_photon_flux_error Uncertainty in the Observed NuSTAR 10-40 keV Flux photon/s/cm^2 stat.error;phot.flux;em.X-ray.hard double nullable association_flag Group Number meta.code short nullable trial_map_value Trial Map Value at the Chandra Position stat.param double nullable sb_photon_flux_flag Flag Indicates Note Concerning the Uncertainty in Observed NuSTAR 3-10 keV Flux meta.code;phot.flux;em.X-ray.medium char nullable hardness_ratio_error Uncertainty in BEHR stat.error;phot.flux;arith.ratio;em.X-ray double nullable sb_photon_flux The Observed NuSTAR 3-10 keV Flux photon/s/cm^2 phot.flux;em.X-ray.medium double nullable trial_map_band_upper Energy Band of the Trial Map with the Local Peak Value, Upper Value keV short nullable aperture_id_2 Source and Background Aperture Radii Flag, for the Second Aperture Set meta.code char nullable quartile_ratio_flag Flag Indicates Note Concerning the Uncertainty in Quartile Ratio meta.code;stat.param char nullable hb_lx_flag Flag Indicates Note Concerning the Observed NuSTAR 10-40 keV Luminosity at 8 kpc meta.code;phys.luminosity;em.X-ray.hard char nullable median_energy Median Energy of the NuSTAR Spectrum in 3-40 keV keV phys.energy double nullable hardness_ratio_flag Flag Indicates Note Concerning the Uncertainty in BEHR meta.code;phot.flux;arith.ratio;em.X-ray char nullable detect_bands [S/H/SH] Indicates Detection in the Soft (S<10keV) and/or Hard (H>10keV) Bands meta.code char nullable chandra_name Chandra Counterpart Designation (CXOGC JHHMMSS.s+DDMMSS) meta.id.cross char nullable aperture_id_1 Source and Background Aperture Radii Flag, for the First Aperture Set meta.code char nullable exposure Combined Exposure of the Two NuSTAR FPMs at the Chandra Source Position s time.duration;obs.exposure double nullable hb_photon_flux_flag Flag Indicates Note Concerning the Uncertainty in Observed NuSTAR 10-40 keV Flux meta.code;phot.flux;em.X-ray.hard char nullable field_name Field Designation meta.id;obs.field char nullable aperture_id_1_flag Flag [a] Indicates Note Concerning the First Aperture Set Radii meta.code char nullable sb_photon_flux_error Uncertainty in the Observed NuSTAR 3-10 keV Flux photon/s/cm^2 stat.error;phot.flux;em.X-ray.medium double nullable nh Estimate of Hydrogen Column Density Along the Line of Sight cm^-2 phys.columnDensity double nullable lii Galactic Longitude degree pos.galactic.lon double nullable sb_lx_flag Flag Indicates Note Concerning the Observed NuSTAR 3-10 keV Luminosity at 8 kpc meta.code;phys.luminosity;em.X-ray.medium char nullable trial_map_band_lower Energy Band of the Trial Map with the Local Peak Value, Lower Value keV short nullable spectral_index Estimate of Photon Index Using the Median Energy for Absorbed Power-Law Model spect.index double nullable median_energy_flag Flag Indicates Note Concerning the Uncertainty in Median Energy meta.code;phys.energy char nullable aperture_id_2_flag Flag [a] Indicates Note Concerning the Second Aperture Set Radii meta.code char nullable chandra_source_number Chandra Counterpart Identifier by Muno et al. 2009 (J/ApJS/181/110) meta.id.cross short nullable num_trial_map_detects Number of trial maps above their respective thresholds at the Chandra Position meta.number short nullable source_number Sequential Identification Number for Each Source in the Catalog meta.id;src short nullable quartile_ratio A Relative Ratio of 25% and 75% Quartiles: 3(E_25 - 3 keV)/(E_75 - 3 keV) stat.param double nullable spectral_index_flag Flag Indicates Note Concerning the Uncertainty in Spectral Index meta.code;spect.index char nullable nustar_flags NuSTAR Flags meta.code char nullable trial_map_psf_fraction Source cell Size of the trial Map with the local Peak Value percent instr.det.psf short nullable comments A Known Name, Nearby Chandra Source, and/or Notable Diffuse Feature Nearby meta.note char nullable hb_photon_flux The Observed NuSTAR 10-40 keV Flux photon/s/cm^2 phot.flux;em.X-ray.hard double nullable spectral_index_error Uncertainty in Spectral Index stat.error;spect.index double nullable median_energy_error Uncertainty in Median Energy keV stat.error;phys.energy double nullable bii Galactic Latitude degree pos.galactic.lat double nullable hardness_ratio Mode of Posterior Distribution of Bayesian Enhanced X-Ray Hardness Ratio (BEHR) phot.flux;arith.ratio;em.X-ray double nullable chandra_photon_flux The Observed (i.e., Absorbed) Chandra 2-8 keV Flux photon/cm^2/s phot.flux;em.X-ray double nullable quartile_ratio_error Uncertainty in Quartile Ratio stat.error;stat.param 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 off_set Angular Offset Between the NuSTAR and Chandra Positions arcsec pos.angDistance double nullable