Carina Nebula Gum 31 Chandra X-Ray Point Source Catalog CARGM31CXO ivo://nasa.heasarc/cargm31cxo NASA/GSFC HEASARC Preibisch et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source Gum 31 is a prominent, but still rather poorly studied, HII region around the stellar cluster NGC 3324 at the northwestern periphery of the Carina nebula complex. The aim of the authors aim was to reveal and characterize the young stellar population in Gum 31. An X-ray survey is the only efficient way to identify young stars in this region, which has extremely high galactic field-star contamination, that can avoid the strong biases of infrared-excess-selected samples of disk-bearing young stars. The authors used the Chandra observatory to perform a deep (70 ks) X-ray observation of the Gum 31 region and detected 679 X-ray point sources. This extends and complements the X-ray survey of the central Carina nebula regions performed in the Chandra Carina Complex Project (CCCP, available in the HEASARC database system as the CARINACXO table). Using deep near-infrared images from their recent VISTA survey of the Carina nebula complex, their comprehensive Spitzer point-source catalog, and optical archive data, the authors identify counterparts for 75% of these X-ray sources. The aimpoint of the ACIS-I observation was set to be RA(J2000) = 10<sup>h</sup> 37<sup>m</sup> 36.6<sup>s</sup>, Dec(J2000) = -58<sup>o</sup> 41' 18". This position is close to the center of the H II region, and allows both the stellar cluster NGC 3324 and the cluster G286.38-0.26 to be in the inner parts of the field-of-view, where the point-spread function is still very good. The pointing roll angle (i.e., the orientation of the detector with respect to the celestial north direction) was 138.35<sup>o</sup>. The ACIS field-of-view is just wide enough to cover the full spatial extent of the optically bright Gum 31 H II region and some parts of the surrounding dust shell (see Fig. 1 of the reference paper). The ACIS-I field of view is 17' x 17', which corresponds to 11.3 p x 11.3 pc at the Gum 31 distance of 2.3 kpc). The total net exposure time of the observation was 68,909s (19.14 h). The details of the source detection procedures are described in Section 21. of the reference paper. The final X-ray catalog contains 679 individual point sources. The number of extracted counts ranges from 3 for the faintest sources, up to 920 for the strongest source, while the median value is 11 counts. This table contains the basic X-ray properties and near- and mid-infrared photometry of the X-ray sources detected in the Gum 31 field. The details of the IR matching to the X-ray sources are given in Sections 4.1, 4.2 and 4.3 of the reference paper. This table was created by the HEASARC in May 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/564/A120">CDS Catalog J/A+A/564/A120</a> files table1.dat and table3.dat. This is a service provided by NASA HEASARC . 2014A&A...564A.120P https://heasarc.gsfc.nasa.gov/W3Browse/all/cargm31cxo.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=cargm31cxo& GET text/xml 180 99999 true 159.474966 -58.843194 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=cargm31cxo GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_cargm31cxo&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 Infrared X-ray public cargm31cxo Carina Nebula Gum 31 Chandra X-Ray Point Source Catalog source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable name IAU Designation of the X-Ray Source (CXOPMTB 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 fb_counts Net Counts in the Total Energy Band (0.5-8keV) ct phot;em.X-ray double nullable fb_counts_error 1-Sigma errors on Net Counts ct stat.error;phot;em.X-ray double nullable ir_name IAU Designation of the Corresponding VISTA or 2MASS Source meta.id.cross;em.IR char nullable jmag Near-Infrared Photometry in the J Band mag phot.mag;em.IR.J double nullable hmag Near-Infrared Photometry in the H Band mag phot.mag;em.IR.H double nullable ks_mag Near-Infrared Photometry in the K_s Band mag phot.mag;em.IR.K double nullable irac_3p6_um_mag Mid-Infrared Photometry in the Spitzer IRAC 1 Band mag phot.mag;em.IR.3-4um double nullable off_axis Off-Axis Angle arcmin instr.offset 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 ks_mag_snr Signal-to-Noise Ratio of the Ks Band Flux Measurement stat.snr;phot.mag;em.IR.K double nullable log_prob_no_src_limit Limit Flag for Logarithm of Probability That Extracted Counts Are Background meta.code;stat.probability;src;em.X-ray char nullable median_energy Background-Corrected Median Photon Energy (Total Band) keV phys.energy double nullable hmag_snr Signal-to-Noise Ratio of the H Band Flux Measurement stat.snr;phot.mag;em.IR.H double nullable irac_3p6_um_mag_snr Signal-to-Noise Ratio of the IRAC 1 Band Flux Measurement stat.snr;phot.mag;em.IR.3-4um double nullable log_prob_no_src Logarithm of Probability That Extracted Counts (Total Band) Are from Background stat.probability;src;em.X-ray double nullable error_radius Position Error arcsec stat.error;pos double nullable irac_5p8_um_mag Mid-Infrared Photometry in the Spitzer IRAC 3 Band mag phot.mag;em.IR.4-8um double nullable psf_fraction Fraction of the PSF (at 1.497keV) Enclosed within the Extraction Region instr.det.psf double nullable anomalies_flag Flag [g] Indicates Source Anomalies meta.code char nullable fb_bck_counts Background Counts Expected in the Source Extraction Region (Total Band) ct phot;instr.background;em.X-ray double nullable lii Galactic Longitude degree pos.galactic.lon double nullable ir_flag Flag [012] Indicates the Source of the Photometry meta.code short nullable irac_5p8_um_mag_snr Signal-to-Noise Ratio of the IRAC 3 Band Flux Measurement stat.snr;phot.mag;em.IR.4-8um double nullable ks_var_statistic Flag [abc] Indicates Variability Characterization Based on K-S Statistic stat.probability;src.var;em.X-ray char nullable bii Galactic Latitude degree pos.galactic.lat double nullable hb_counts Net Counts in the Hard Energy Band (2-8keV) ct phot;em.X-ray.medium double nullable jmag_snr Signal-to-Noise Ratio of the J Band Flux Measurement stat.snr;phot.mag;em.IR.J double nullable irac_4p5_um_mag_snr Signal-to-Noise Ratio of the IRAC 2 Band Flux Measurement stat.snr;phot.mag;em.IR.4-8um double nullable irac_4p5_um_mag Mid-Infrared Photometry in the Spitzer IRAC 2 Band mag phot.mag;em.IR.4-8um double nullable significance Photometric Significance stat.likelihood;phot;em.X-ray double nullable irac_8p0_um_mag_snr Signal-to-Noise Ratio of the IRAC 4 Band Flux Measurement stat.snr;phot.mag;em.IR.4-8um double nullable spitzer_name IAU Designation of the Corresponding Spitzer Source meta.id.cross;em.IR char nullable irac_8p0_um_mag Mid-Infrared Photometry in the Spitzer IRAC 4 Band mag phot.mag;em.IR.4-8um double nullable