NGC253XMM ivo://nasa.heasarc/ngc253xmm NASA/GSFC HEASARC Barnard et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains the NGC 253 XMM-Newton X-Ray Point Source Catalog. NGC 253 is a local, starbursting spiral galaxy with strong X-ray emission from hot gas, as well as many point sources. The authors have conducted a spectral survey of the X-ray population of NGC 253 using a deep XMM-Newton observation. NGC 253 only accounts for ~20 per cent of the XMM-Newton EPIC field of view, allowing them to identify ~ 100 X-ray sources that are unlikely to be associated with NGC 253. Hence, they were able to make a direct estimate of contamination from, for example, foreground stars and background galaxies. X-ray luminosity functions (XLFs) of galaxy populations are often used to characterize their properties. There are several methods for estimating the luminosities of X-ray sources with few photons. The authors have obtained spectral fits for the brightest 140 sources in the 2003 XMM-Newton observation of NGC 253, and compare the best-fitting luminosities of those 69 non-nuclear sources associated with NGC 253 with luminosities derived using other methods. They find the luminosities obtained from these various methods to vary systematically by a factor of up to 3 for the same data; this is largely due to differences in absorption. The authors therefore conclude that assuming Galactic absorption is probably unwise; rather, one should measure the absorption for the population. In addition, they find that standard estimations of the background contribution to the X-ray sources in the field are insufficient, and that the background active galactic nuclei (AGN) may be systematically more luminous than previously expected. However, the excess in their measured AGN XLF with respect to the expected XLF may be due to an as yet unrecognized population associated with NGC253. XMM-Newton observations are susceptible to periods of high background levels, caused by increased flux of solar particles. The authors screened the data from each of the EPIC cameras (MOS1, MOS2 and pn), to remove flaring intervals. This process resulted in ~ 46 ks of good time for the pn and ~ 69 ks for the MOS cameras. The authors combined the cleaned MOS and pn data, and ran the source detection algorithm provided with the XMM-Newton data analysis suite SAS version 7.0. They accepted sources with maximum-likelihood detections > 10 (equivalent to 4 sigma). This table was created by the HEASARC in April 2009 based on the electronic version of Tables A1 and A2 from the paper which were obtained from the CDS (their catalog J/MNRAS/388/849 files tablea1.dat and tablea2.dat). This is a service provided by NASA HEASARC . 2008MNRAS.388..849B https://heasarc.gsfc.nasa.gov/W3Browse/all/ngc253xmm.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=ngc253xmm& GET text/xml 180 99999 true 11.85858333 -25.5629 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=ngc253xmm GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_ngc253xmm&Action=More+Options&Action=Parameter+Search&ConeAdd=1 XMM-NEWTON 0.0166666666666667 X-ray public ngc253xmm NGC 253 XMM-Newton 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 pn_counts PN Source Counts ct phot;em.X-ray int nullable lx_best Best-Fitting Luminosity erg/s phys.luminosity;em.X-ray double nullable lx_best_error RMS Uncertainty of Best-Fitting Luminosity at 90% Confidence Level erg/s stat.error;phys.luminosity;em.X-ray double nullable nh_flag Flag [f] Indicates Fixed Absorption meta.code;phys.columnDensity char nullable eef Encircled Energy Fraction instr.det.psf double nullable spect_param_2 Second Parameter Value (Spectral Index or Temperature) stat.param;spect double nullable spectral_model Best-Fitting Model meta.code;spect;meta.modelled char nullable spect_param_1_error RMS Uncertainty of Parameter at 90% Confidence Level stat.error;stat.param;spect double nullable dof Degrees of Freedom stat.fit.dof;spect short nullable good_fit_prob Good Fit Probability stat.probability;spect double nullable extraction_radius Source Extraction Radius arcsec phys.angSize short nullable mos_counts MOS Source Counts ct phot;em.X-ray int nullable spect_param_2_error RMS Uncertainty of Second Parameter at 90% Confidence Level stat.error;stat.param;spect double nullable in_d25_flag Flag [YN] Indicates Whether Source Is Within the D25 Region of NGC 253 meta.code;pos char nullable nh_error RMS Uncertainty of NH at 90% Confidence Level H-atoms/cm^2 stat.error;phys.columnDensity double nullable bck_src_area_ratio Background-to-Source Area Ratio meta.code;phys.angArea double nullable chi_squared Chi^2 Value stat.fit.chi2;spect 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 nh Absorption H-atoms/cm^2 phys.columnDensity double nullable lx_standard Standard Model (Method I) Luminosity erg/s phys.luminosity;em.X-ray double nullable spect_param_1 Parameter (Spectral Index or Temperature) stat.param;spect double nullable lii Galactic Longitude degree pos.galactic.lon 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