Chan/XAssist ivo://nasa.heasarc/cxoxassist NASA/GSFC HEASARC Ptak, Griffiths 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This database table contains the latest Chandra XAssist source list. XAssist is a NASA-funded project for the automation of X-ray astrophysics, with emphasis on galaxies. It is capable of data reprocessing, source detection, and preliminary spatial, temporal, and spectral analysis for all sources with sufficient counts. The bulk of the system is written in Python, which in turn drives underlying software, e.g., CIAO for Chandra data. Pipelines running on Chandra observations of galaxies have generated the source list which comprises this HEASARC table. The pipeline also includes fields requested by users for various projects, most notably observations of a sample of quasars and several deep field observations have been processed. Note that the pipline processing is completely automated; therefore, users should visually inspect the results of any queries. This table was first created by the HEASARC in May 2005 based on the Chandra source list available at the XAssist website. In September 2010, the HEASARC switched over to using the "pipeline4" Chandra source list. It is updated on a weekly basis when and if the XAssist source list file at <a href="https://asd.gsfc.nasa.gov/xassist/pipeline4/chandra/">https://asd.gsfc.nasa.gov/xassist/pipeline4/chandra/</a> is updated. This is a service provided by NASA HEASARC . 2003ASPC..295..465P https://heasarc.gsfc.nasa.gov/W3Browse/all/cxoxassist.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cxoxassist& GET text/xml 180 99999 true 300.835710275 -85.7225423759 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cxoxassist GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cxoxassist&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public cxoxassist Chandra XAssist Source List name Source Designation meta.id;meta.main char nullable html_file Link to HTML File with Additional Information char nullable ra Right Ascension degree pos.eq.ra;meta.main double nullable dec Declination degree pos.eq.dec;meta.main double nullable counts Counts ct phot;em.X-ray double nullable counts_error Error in Counts ct stat.error;phot double nullable flux Flux (erg/s/cm^2) erg/s/cm^2 phot.flux;em.X-ray double nullable exposure Net Exposure (s) s time.duration;obs.exposure 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 detector Chandra Detector char nullable nh_gal Galactic Hydrogen Column Density (H-atoms/cm^2) H-atoms/cm^2 double nullable fit_nh_pos_err Best Fit Galactic Hydrogen Column Density Positive Error Bar (H-atoms/cm^2) H-atoms/cm^2 double nullable x_pixel X Pixel pixel pos.cartesian.x;instr.pixel double nullable b_scale Background Region Size Scale (degree^2) degree^2 double nullable hardness_ratio_error Error in Hardness Ratio stat.error;phot.flux;arith.ratio;em.X-ray.medium;em.X-ray.soft double nullable hardness_ratio Hardness Ratio phot.flux;arith.ratio;em.X-ray.medium;em.X-ray.soft double nullable major_axis_neg_err Major Axis Negative Error Bar (arcsec) arcsec double nullable snr Signal-to-Noise Ratio stat.snr double nullable aperture_counts_error Error in Aperture Counts ct double nullable position_angle_neg_err Position Angle Negative Error Bar (degree) degree stat.error;pos.posAng double nullable position_angle Position Angle (degree) degree pos.posAng double nullable minor_axis_neg_err Minor Axis Negative Error Bar (arcsec) arcsec double nullable soft_bckgrd_counts Soft Background Counts ct double nullable simplespat_counts Simple Spatial Counts ct double nullable soft_counts Soft Counts ct double nullable count_rate Count Rate (ct/s) ct/s phot.count;em.X-ray double nullable y_pixel Y Pixel pixel pos.cartesian.y;instr.pixel double nullable version Version char nullable hard_counts Hard Counts ct double nullable count_rate_error Error in Count Rate (ct/s) ct/s stat.error;phot.count;em.X-ray double nullable fit_photon_index Best Fit Photon Index double nullable lii Galactic Longitude degree pos.galactic.lon double nullable fit_nh_neg_err Best Fit Galactic Hydrogen Column Density Negative Error Bar (H-atoms/cm^2) H-atoms/cm^2 double nullable off_axis_angle Off-Axis Angle (arcmin) arcmin double nullable extent_flag Flag Indicates Extent char nullable fit_flux Best Fit Flux (erg/s/cm^2) erg/s/cm^2 double nullable simplespat_bckgrd_counts Simple Spatial Background Counts ct double nullable source_number Source Number meta.id short nullable major_axis_pos_err Major Axis Positive Error Bar (arcsec) arcsec double nullable source_flags Source Flags meta.code;src char nullable hard_bckgrd_counts Hard Background Counts ct double nullable det_y Detector Coordinate Y of the Source Detection double nullable s_scale Source Region Size Scale (degree^2) degree^2 double nullable aperture_bckgrd_counts Aperture Background Counts ct double nullable det_x Detector Coordinate X of the Source Detection double nullable fit_photon_index_pos_err Best Fit Photon Index Positive Error Bar double nullable bckgrd_counts Background Counts ct double nullable initial_exposure Initial Exposure (s) s double nullable minor_axis Minor Axis (arcsec) arcsec double nullable minor_axis_pos_err Minor Axis Positive Error Bar (arcsec) arcsec double nullable aperture_counts Aperture Counts ct double nullable position_angle_pos_err Position Angle Positive Error Bar (degree) degree stat.error;pos.posAng double nullable fit_nh Best Fit Galactic Hydrogen Column Density (H-atoms/cm^2) H-atoms/cm^2 double nullable aper_count_rate_error Error in Aperture Count Rate (ct/s) ct/s double nullable probability Probability double nullable fit_chi_squared Chi Squared of Best Fit double nullable major_axis Major Axis (arcsec) arcsec double nullable aper_count_rate Aperture Count Rate (ct/s) ct/s double nullable bii Galactic Latitude degree pos.galactic.lat double nullable field_name Chandra Field Designation char nullable variability_flag Flag Indicates Variability char nullable fit_dof Degrees of Freedom of Best Fit int nullable fit_photon_index_neg_err Best Fit Photon Index Negative Error Bar double nullable