NGC 404 Chandra X-Ray Point Source Catalog

NGC 404 Chandra X-Ray Point Source Catalog NGC404CXO ivo://nasa.heasarc/ngc404cxo 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 a comprehensive X-ray point-source catalog of NGC 404, the closest face-on (inclination angle of 11 degrees) S0 galaxy to the Milky Way, which was obtained as part of the Chandra Local Volume Survey (CLVS) and originally published in Binder et al. (2013). A new 97-ks Chandra ACIS-S observation of NGC 404 was combined with archival observations for a total exposure of ~123 ks. This survey yields 74 highly significant X-ray point sources and is sensitive to a limiting unabsorbed luminosity of ~6 x 1035 erg/s in the 0.35-8 keV band. To constrain the nature of each X-ray source, cross-correlations with multi-wavelength data were generated. The authors searched overlapping Hubble Space Telescope (HST) observations for optical counterparts to their X-ray detections, but found only two X-ray sources with candidate optical counterparts. They found 21 likely low-mass X-ray binaries (LMXBs), although this number is a lower limit due to the difficulties in separating LMXBs from background active galactic nuclei (AGN). The X-ray luminosity functions (XLFs) in both the soft and hard energy bands are presented in the 2013 reference paper. The XLFs in the soft band (0.5-2 keV) and the hard band (2-8 keV) have a limiting luminosity at the 90% completeness limit of 1035 erg/s and 1036 erg/s, respectively, significantly lower than previous X-ray studies of NGC 404. The authors find the XLFs to be consistent with those of other X-ray populations dominated by LMXBs. However, the number of luminous (>1037 erg/s) X-ray sources per unit stellar mass in NGC 404 is lower than is observed for other galaxies. The relative lack of luminous XRBs may be due to a population of LMXBs with main-sequence companions formed during an epoch of elevated star formation ~0.5 Gyr ago. NGC 404 was observed during Chandra X-Ray Observatory Cycle 12 on 2010 October 21-22 for 97 ks using the ACIS-S array (Obs. ID 12339). The authors additionally utilized archival observations: NGC 404 was observed on 1999 December 19 (Obs. ID 870) for ~24 ks and on 2000 August 30 (Obs. ID 384) for ~2 ks, both using the ACIS-S array. The authors created images in the following energy bands (keV): 0.35-8.0, 0.35-1.0, 1.0-2.0, 2.0-8.0 with bin sizes of 1, 2, 3, and 4. The iterative source detection strategy that was used is described in Section 2.3 of Binder et al. (2012, ApJ, 758, 15). 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 or 0.35 - 8.0 keV. To be included in the final NGC 404 catalog, a source was required to have a pns value less than 4 x 10-6 in any of the nine energy bands. The final CLVS source catalog for NGC 404 contains 74 sources. Given the survey size of these NGC 404 observations, there are expected to be ~1.6 false sources included in this NGC 404 final source catalog. Three HST fields were used to search for optical counterparts for each of the X-ray sources. One field (labeled "DEEP") was taken as part of the Advanced Camera for Surveys (ACS) Nearby Galaxy Survey Treasury (ANGST, GO-10915; Dalcanton et al. 2009, ApJS, 183, 67), while the other two shallower fields (labeled "NE" and "SW") were obtained as part of GO-11986. Details of the HST data acquisition and data reduction are provided in Williams et al. (2010, ApJ, 716, 71). This table was created by the HEASARC in September 2015 primarily based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/763/128">CDS Catalog J/ApJ/763/128</a> files table3.dat, table4.dat, table5.dat, table6.dat, table10.dat, table12.dat and table13.dat (Binder et al. 2013) which contain the properties of the 74 Chandra point sources found in this study.and of their multi-wavelength counterparts. As noted above, the HEASARC has added an extra parameter b4_flux which was taken from the machine-readable version of Table 5 of Binder et al. (2015). This is a service provided by NASA HEASARC . 2015AJ....150...94B https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc404cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc404cxo& GET text/xml 180 99999 true 17.255343 35.639272 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc404cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc404cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc404cxo NGC 404 Chandra X-Ray Point Source Catalog source_number Sequential Identification Number for Each Source in the Catalog meta.id;src short nullable name Source Identifier (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 Circle Around Source arcsec stat.error;pos double nullable b4_counts Net Counts in the 0.35-8keV Energy Band ct phot;em.X-ray double nullable b4_counts_neg_err Lower Uncertainty in Net Counts in the 0.35-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b4_counts_pos_err Upper Uncertainty in Net Counts in the 0.35-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b4_log_photon_flux Logarithm of 0.35-8keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable b4_flux Unabsorbed X-Ray Flux in the 0.35-8keV Energy Band erg/s/cm^2 phot.flux;em.X-ray double nullable source_type Object Classification: AGN, XRB, SSS, FS (Foreground Star), NUCLEUS (of NGC 404) src.class char 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 flux_1p4_ghz NVSS 1.4GHz Flux Density mJy phot.flux.density;em.radio.750-1500MHz double nullable b5_log_prob_ns_limit Limit Flag for Non-Source Probability, 0.35-1.1keV meta.code;stat.probability;src;em.X-ray char nullable extraction_radius Average Radius of Extraction Region pixel phys.angSize;instr.det double nullable b7_log_photon_flux Logarithm of 2.6-8keV Energy Band Photon Flux (4) log(cm^-2/s) phot.flux;em.X-ray double nullable b7_counts_limit Limit Flag for Net Counts in the 2.6-8keV Energy Band meta.code;phot;em.X-ray char nullable b4_log_prob_ns_limit Limit Flag for Non-Source Probability, 0.35-8keV meta.code;stat.probability;src;em.X-ray char nullable b4_log_prob_ns Non-Source Probability, 0.35-8keV stat.probability;src;em.X-ray double nullable b2_log_prob_ns Non-Source Probability, 0.5-2keV stat.probability;src;em.X-ray double nullable b5_counts_neg_err Lower Uncertainty in Net Counts in the 0.35-1.1keV Energy Band ct stat.error;phot;em.X-ray double nullable ks_mag 2MASS K_s-Band Magnitude mag phot.mag;em.IR.K double nullable b2_log_prob_ns_limit Limit Flag for Non-Source Probability, 0.5-2keV meta.code;stat.probability;src;em.X-ray char nullable galex_nuv_mag GALEX GR6 NUV Magnitude mag phot.mag;em.UV.200-300nm double nullable b2_counts_pos_err Upper Uncertainty in Net Counts in the 0.5-2keV Energy Band ct stat.error;phot;em.X-ray double nullable b2_counts_neg_err Lower Uncertainty in Net Counts in the 0.5-2keV Energy Band ct stat.error;phot;em.X-ray double nullable bii Galactic Latitude degree pos.galactic.lat double nullable hardness_ratio_class Classification of Source src.class char nullable b8_counts_pos_err Upper Uncertainty in Net Counts in the 0.35-2keV Energy Band ct stat.error;phot;em.X-ray double nullable jmag_error 2MASS J-Band Magnitude Uncertainty mag stat.error;phot.mag;em.IR.J double nullable b7_counts_neg_err Lower Uncertainty in Net Counts in the 2.6-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b7_counts Net Counts in the 2.6-8keV Energy Band ct phot;em.X-ray double nullable b6_counts Net Counts in the 1.1-2.6keV Energy Band ct phot;em.X-ray double nullable b6_log_prob_ns Non-Source Probability, 1.1-2.6keV stat.probability;src;em.X-ray double nullable mean_expo_map_value Total Exposure Map Value in Source Region s.cm^2 meta.number;obs.exposure double nullable b3_counts_limit Limit Flag for Net Counts in the 2-8keV Energy Band meta.code;phot;em.X-ray char nullable b6_log_photon_flux Logarithm of 1.1-2.6keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable hardness_ratio_1 Hardness Ratio 1 (the Soft Color) phot.flux;arith.ratio;em.X-ray double nullable hst_f606w_mag_error HST F606W Uncertainty mag stat.error;phot.mag;em.opt.V double nullable b8_counts Net Counts in the 0.35-2keV Energy Band ct phot;em.X-ray double nullable hardness_ratio_2_error Uncertainty in HR2 stat.error;phot.flux;arith.ratio;em.X-ray double nullable b6_counts_neg_err Lower Uncertainty in Net Counts in the 1.1-2.6keV Energy Band ct stat.error;phot;em.X-ray double nullable ks_mag_error 2MASS K_s-Band Magnitude Uncertainty mag stat.error;phot.mag;em.IR.K double nullable b8_counts_limit Limit Flag for Net Counts in the 0.35-2keV Energy Band meta.code;phot;em.X-ray char nullable b2_log_photon_flux Logarithm of 0.5-2keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable b3_log_photon_flux Logarithm of 2-8keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable b3_log_prob_ns_limit Limit Flag for Non-Source Probability, 2-8keV meta.code;stat.probability;src;em.X-ray char nullable b5_counts_pos_err Upper Uncertainty in Net Counts in the 0.35-1.1keV Energy Band ct stat.error;phot;em.X-ray double nullable b1_counts_neg_err Lower Uncertainty in Net Counts in the 0.5-8keV Energy Band ct stat.error;phot;em.X-ray double nullable bmag USNO-B1 B-Band Magnitude mag phot.mag;em.opt.B double nullable rmag USNO-B1 R-Band Magnitude mag phot.mag;em.opt.R double nullable b6_counts_limit Limit Flag for Net Counts in the 1.1-2.6keV Energy Band meta.code;phot;em.X-ray char nullable flux_1p4_ghz_error NVSS 1.4GHz Flux Density Uncertainty mJy stat.error;phot.flux.density;em.radio.750-1500MHz double nullable b8_log_prob_ns_limit Limit Flag for Non-Source Probability, 0.35-2keV meta.code;stat.probability;src;em.X-ray char nullable b3_counts Net Counts in the 2-8keV Energy Band ct phot;em.X-ray double nullable galex_nuv_mag_error GALEX GR6 NUV Magnitude Uncertainty mag stat.error;phot.mag;em.UV.200-300nm double nullable galex_fuv_mag_error GALEX GR6 FUV Magnitude Uncertainty mag stat.error;phot.mag;em.UV.100-200nm double nullable b7_log_prob_ns_limit Limit Flag for Non-Source Probability, 2.6-8keV meta.code;stat.probability;src;em.X-ray char nullable hardness_ratio_2 Hardness Ratio 2 (the Hard Color) phot.flux;arith.ratio;em.X-ray double nullable b5_log_prob_ns Non-Source Probability, 0.35-1.1keV stat.probability;src;em.X-ray double nullable b8_log_prob_ns Non-Source Probability, 0.35-2keV stat.probability;src;em.X-ray double nullable hardness_ratio_1_error Uncertainty in HR1 stat.error;phot.flux;arith.ratio;em.X-ray double nullable b7_log_prob_ns Non-Source Probability, 2.6-8keV stat.probability;src;em.X-ray double nullable counterpart_flags Values Indicate Wavelength Counterpart(s) meta.code char nullable off_axis Off-Axis Angle (Theta) arcmin instr.offset double nullable hst_f814w_mag_error HST F814W Uncertainty mag stat.error;phot.mag;em.opt.I double nullable b1_counts Net Counts in the 0.5-8keV Energy Band ct phot;em.X-ray double nullable hmag 2MASS H-Band Magnitude mag phot.mag;em.IR.H double nullable best_spectral_fit Best Spectral Fit meta.code;meta.modelled char nullable hst_f814w_mag HST F814W Band Magnitude mag phot.mag;em.opt.I double nullable b8_log_photon_flux Logarithm of 0.35-2keV Energy Band Photon Flux (4) log(cm^-2/s) phot.flux;em.X-ray double nullable b1_log_prob_ns_limit Limit Flag for Non-Source Probability, 0.5-8keV meta.code;stat.probability;src;em.X-ray char nullable hmag_error 2MASS H-Band Magnitude Uncertainty mag stat.error;phot.mag;em.IR.H double nullable b5_counts Net Counts in the 0.35-1.1keV Energy Band ct phot;em.X-ray double nullable b6_counts_pos_err Upper Uncertainty in Net Counts in the 1.1-2.6keV Energy Band ct stat.error;phot;em.X-ray double nullable b7_counts_pos_err Upper Uncertainty in Net Counts in the 2.6-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b1_log_photon_flux Logarithm of 0.5-8keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable b8_counts_neg_err Lower Uncertainty in Net Counts in the 0.35-2keV Energy Band ct stat.error;phot;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable b5_log_photon_flux Logarithm of 0.35-1.1keV Energy Band Photon Flux log(cm^-2/s) phot.flux;em.X-ray double nullable galcen_radius Galactocentric Distance kpc phys.size.radius double nullable b3_log_prob_ns Non-Source Probability, 2-8keV stat.probability;src;em.X-ray double nullable b1_counts_pos_err Upper Uncertainty in Net Counts in the 0.5-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b2_counts Net Counts in the 0.5-2keV Energy Band ct phot;em.X-ray double nullable variability Value Indicates Variability (long or rapid) src.var char nullable galex_fuv_mag GALEX GR6 FUV Magnitude mag phot.mag;em.UV.100-200nm double nullable b3_counts_neg_err Lower Uncertainty in Net Counts in the 2-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b5_counts_limit Limit Flag for Net Counts in the 0.35-1.1keV Energy Band meta.code;phot;em.X-ray char nullable hst_f606w_mag HST F606W Band Magnitude mag phot.mag;em.opt.V double nullable jmag 2MASS J-Band Magnitude mag phot.mag;em.IR.J double nullable b3_counts_pos_err Upper Uncertainty in Net Counts in the 2-8keV Energy Band ct stat.error;phot;em.X-ray double nullable b1_log_prob_ns Non-Source Probability, 0.5-8keV stat.probability;src;em.X-ray double nullable b6_log_prob_ns_limit Limit Flag for Non-Source Probability, 1.1-2.6keV meta.code;stat.probability;src;em.X-ray char nullable