NGC 4278 Chandra X-Ray Point Source Catalog

NGC 4278 Chandra X-Ray Point Source Catalog NGC4278CXO ivo://nasa.heasarc/ngc4278cxo NASA/GSFC HEASARC Brassington et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table lists some of the properties of the discrete X-ray sources detected in the authors' monitoring program of the globular cluster (GC)-rich elliptical galaxy, NGC 4278, observed with Chandra ACIS-S in six separate pointings, resulting in a co-added exposure of 458 ks. From this deep observation, 236 sources have been detected within the region overlapped by all observations, 180 of which lie within the D25 ellipse angular diameter of the galaxy. These 236 sources range in X-ray luminosity LX from 3.5 x 1036 erg s-1 (with 3-sigma upper limit <= 1 x 1037 erg s-1) to ~2 x 1040 erg s-1, including the central nuclear source which has been classified as a LINER. From optical data, 39 X-ray sources have been determined to be coincident with a GC, these sources tend to have high X-ray luminosity, with 10 of these sources exhibiting LX > 1 x 1038 erg s-1. From X-ray source photometry, it has been determined that the majority of the 236 point sources that have well-constrained colors have values that are consistent with typical low-mass X-ray binary spectra, with 29 of the sources expected to be background objects from the log N-log S relation. There are 103 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. Three of these sources have been identified as transient candidates, with a further three possible transients. Spectral variations have also been identified in the majority of the source population, where a diverse range of variability has been identified, indicating that there are many different source classes located within this galaxy. This HEASARC table contains the master source list (Table 3 of the reference paper) and the X-ray properties of the sources in the co-added observations (Table 4 of the reference paper), but not the X-ray properties of the sources in the 6 individual observations (Tables 5-10 of the reference paper). The details of the six individual pointings used in this study, e.g., the Chandra ObsIDs, dates, exposure times and cleaned exposure times, are given in Table 1 of the reference paper, and repeated here: <pre> Obs. No.OBSID Date Exposure (s) Cleaned Exposure (s) 1 4741 2005 Feb 3 37462.0 37264.5 2 7077 2006 Mar 16 110303.8 107736.7 3 7078 2006 Jul 25 51433.2 48076.2 4 7079 2006 Oct 24 105071.7 102504.6 5 7081 2007 Feb 20 110724.0 107564.5 6 7080 2007 Apr 20 55824.8 54837.5 Total Co-added 470819.5 457984.0 </pre> Notes. The pointing OBSID 7181 was taken before OBSID 7080, so to maintain the time sequence of the exposures these observation numbers have been labeled as above in the reference paper. The details of the energy bands and X-ray colors used in this study are given in Table 2 of the reference paper, and repeated here: <pre> Band/Color Energy Range/Definition Broad (B) 0.3-8 keV Soft (S) 0.3-2.5 keV Hard (H) 2.5-8 keV Soft 1 (S1) 0.3-0.9 keV Soft 2 (S2) 0.9-2.5 keV Conventional broad (Bc) 0.5-8 keV Conventional soft (Sc) 0.5-2 keV Conventional hard (Hc) 2-8 keV Hardness ratio HR (Hc-Sc)/(Hc+Sc) X-ray color C21 -log(S2) + log(S1) = log(S1/S2) X-ray color C32 -log(H) + log(S2) = log(S2/H) </pre> This table was created by the HEASARC in April 2009 based on machine-readable versions of Tables 3 and 4 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC . 2009ApJS..181..605B https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc4278cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc4278cxo& GET text/xml 180 99999 true 185.01334167 29.23478333 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc4278cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc4278cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public ngc4278cxo NGC 4278 Chandra X-Ray Point Source Catalog name IAU-Style Source Designation (CXOU JHHMMSS.s+DDMMSS) 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 Position Uncertainty (arcsec) arcsec stat.error;pos double nullable fb_counts_limit Limit Flag for Net Broad Band (0.3-8 keV) Counts meta.code;phot;em.X-ray char nullable fb_counts Net Broad Band (0.3-8 keV) Counts ct phot;em.X-ray double nullable snr Signal-to-Noise Ratio stat.snr;em.X-ray double nullable log_lx_limit Limit Flag for Log_Lx meta.code;phys.luminosity;em.X-ray char nullable log_lx Logarithm of 0.3-8.0keV Luminosity log(erg/s) phys.luminosity;em.X-ray double nullable center_offset Distance from Galaxy Center (arcsec) arcsec pos.angDistance 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 longterm_var_flag Flag Indicates Long-Term Variability meta.code;src.var;em.X-ray char nullable hb1_counts Net Hard Band (2.5-8 keV) Counts ct phot;em.X-ray.medium double nullable hardness_ratio_pos_err Upper Uncertainty for Hardness Ratio stat.error;phot;arith.ratio;em.X-ray double nullable sb1_counts_error Uncertainty for Net Soft 1 Band (0.3-0.9 keV) Counts ct stat.error;phot;em.X-ray.soft double nullable c32_color The C32 X-ray Color phot;arith.ratio;em.X-ray double nullable sb_counts_error Uncertainty for Net Conventional Soft Band (0.5-2 keV) Counts ct stat.error;phot;em.X-ray.soft double nullable lii Galactic Longitude degree pos.galactic.lon double nullable hardness_ratio Hardness Ratio phot.flux;arith.ratio;em.X-ray double nullable hb_counts Net Conventional Hard Band (2-8 keV) Counts ct phot;em.X-ray.medium double nullable c21_color_pos_err Upper Uncertainty for C21 X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable fb_counts_error Uncertainty for Net Broad Band (0.3-8 keV) Counts ct stat.error;phot;em.X-ray double nullable sb2_counts Net Soft 2 Band (0.9-2.5 keV) Counts ct phot;em.X-ray.soft double nullable sb12_counts Net Soft Band (0.3-2.5 keV) Counts ct phot;em.X-ray.soft double nullable shortterm_ks_flag Flag Indicates Short-Term Variability According to Komogorov-Smirnov Test meta.code;src.var;em.X-ray char nullable source_flag Flag [gl] Indicates Quality of Source: g=S/N > 3 in at least one obs; l=S/N < 3 char nullable hb1_counts_error Uncertainty for Net Hard Band (2.5-8 keV) Counts ct stat.error;phot;em.X-ray.medium double nullable c21_color The C21 X-Ray Color phot;arith.ratio;em.X-ray double nullable hardness_ratio_neg_err Lower Uncertainty for Hardness Ratio stat.error;phot;arith.ratio;em.X-ray double nullable c32_color_neg_err Lower Uncertainty for C32 X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable optical_corr_flag Flag Indicates Optical Association meta.code;src;em.opt char nullable alt_name Alternative Catalog-Based (BFK2009) Source Designation meta.id char nullable c21_color_neg_err Lower Uncertainty for C21 X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable shortterm_bb_flag Flag Indicates Short-Term Variability According to Bayesian Block Analysis meta.code;src.var;em.X-ray char nullable sb12_counts_error Uncertainty for Net Soft Band (0.3-2.5 keV) Counts ct stat.error;phot;em.X-ray.soft double nullable sb_counts Net Conventional Soft Band (0.5-2 keV) Counts ct phot;em.X-ray.soft double nullable bii Galactic Latitude degree pos.galactic.lat double nullable source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable c32_color_pos_err Upper Uncertainty for C32 X-Ray Color stat.error;phot;arith.ratio;em.X-ray double nullable extraction_radius Source Extraction Radius (arcsec) arcsec pos.angDistance double nullable xray_detect_flag Flag Indicates X-Ray Detection Information meta.code char nullable d25_flag Flag [b] Indicates Distance from Galaxy Center Is within the D_25 Ellipse meta.code char nullable log_lx_single The 3-Sigma Upper Limit Value of Log_Lx log(erg/s) phys.luminosity;em.X-ray double nullable sb2_counts_error Uncertainty for Net Soft 2 Band (0.9-2.5 keV) Counts ct stat.error;phot;em.X-ray.soft double nullable sb1_counts Net Soft 1 Band (0.3-0.9 keV) Counts ct phot;em.X-ray.soft double nullable hb_counts_error Uncertainty for Net Conventional Hard Band (2-8 keV) Counts ct stat.error;phot;em.X-ray.medium double nullable