MYSTIXXRAY ivo://nasa.heasarc/mystixxray NASA/GSFC HEASARC Kuhn et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source The Massive Young Star-forming complex Study in Infrared and X-ray (MYStIX) uses data from the Chandra X-Ray Observatory to identify and characterize the young stellar populations in 20 Galactic (d < 4 kpc) massive star-forming regions. In this present study, the X-ray analysis for Chandra ACIS-I observations of 10 of the MYStIX fields is described, and a catalog of > 10,000 X-ray sources is presented in this table. In comparison to other published Chandra source lists for the same regions, the number of MYStIX-detected faint X-ray sources in a region is often doubled. While the higher catalog sensitivity increases the chance of false detections, it also increases the number of matches to infrared stars. X-ray emitting contaminants include foreground stars, background stars, and extragalactic sources. The X-ray properties of sources in these classes are discussed in the reference paper. The X-ray observations were made with the imaging array on the Advanced CCD Imaging Spectrometer (ACIS-I) on board the Chandra X-Ray Observatory. This array of four CCD detectors subtends 17' x 17' on the sky. The number of different Chandra pointings for each region, the total exposures for these pointings, and details of how the observations were taken are provided in Table 1 of the reference paper. Overall, 29 Chandra ObsIDs are included with typical integration times for a pointing of 40 - 100 ks, sufficient to detect most OB stars and lower-mass pre-main-sequence stars down to ~ 0.5 - 1 solar masses for the MYStIX regions. The 10 MYStIX MSFRs treated herein are listed in Table 2 of the reference paper. The data were acquired from the Chandra Data Archive from 2001 Jan to Mar 2008 for 10 MYStIX fields (the Flame Nebula, RCW 36, NGC 2264, the Rosette Nebula, the Lagoon Nebula, NGC 2362, DR 21, RCW 38, Trifid Nebula and NGC 1893). The X-ray photometry is from Broos et al. (2010, ApJ, 714, 1582; ACIS Extract); see also the CCCP, Broos et al. (2011, ApJS, 194, 2). The source significance quantities (fb_prob_no_src, sb_prob_no_src, hb_prob_no_src and prob_no_src_min) are computed using a subset of each source's extractions chosen to maximize significance (Broos et al. 2010, ApJ, 714, 1582, Section 6.2). The source position and positional uncertainty quantities are computed using a subset of each source's extractions chosen to minimize the position uncertainty (Broos et al. 2010, ApJ, 714, 1582, Sections 6.2 and 7.1). All other quantities are computed using a subset of each source's extractions chosen to balance the conflicting goals of minimizing photometric uncertainty and of avoiding photometric bias (Broos et al. 2010, ApJ, 714, 1582, Sections 6.2 and 7). The observed and absorption-corrected energy fluxes and their associated errors and the estimated hydrogen column densities and their uncertainties are derived using non-parametric procedures (XPHOT, Getman et al. 2010, ApJ, 708, 1760). XPHOT assumes the X-ray spectral shapes of young, low-mass stars, which come from coronal X-ray emission. XPHOT quantities will therefore be unreliable for high-mass stars, for which X-ray emission is associated with the stellar wind. This table was created by the HEASARC in January 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/209">CDS Catalog J/ApJS/209</a> 27 file xmystix.dat. This is a service provided by NASA HEASARC . 2013ApJS..209...27K https://heasarc.gsfc.nasa.gov/W3Browse/all/mystixxray.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=mystixxray& GET text/xml 180 99999 true 134.880512 -47.691388 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=mystixxray GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_mystixxray&Action=More+Options&Action=Parameter+Search&ConeAdd=1 CHANDRA 0.0166666666666667 X-ray public mystixxray Massive Young Star-Forming Complex Study in IR & X-Rays: X-Ray S sfr_name Designation of the MYStIX Star-Forming Region meta.id.assoc char nullable name IAU Source Designation (CXO 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 0.5-8keV Counts in Merged Apertures ct phot;em.X-ray double nullable fb_counts_neg_err 1-Sigma Lower Error on Net 0.5-8keV Counts ct stat.error;phot;em.X-ray double nullable fb_counts_pos_err 1-Sigma Upper Error on Net 0.5-8keV Counts ct stat.error;phot;em.X-ray double nullable fb_median_energy Median 0.5-8keV Energy, Observed Spectrum keV phys.energy double nullable fb_flux Absorption-Corrected 0.5-8keV X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable fb_flux_stat_err 1-Sigma Statistical Uncertainty for the Absorption-Corrected 0.5-8keV X-Ray Flux erg/s/cm^2 stat.error;phot.flux;em.X-ray double nullable fb_flux_sys_err 1-Sigma Systematic Uncertainty for the Absorption-Corrected 0.5-8keV X-Ray Flux erg/s/cm^2 stat.error.sys;phot.flux;em.X-ray double nullable sb_arf_value Mean Effective Area (ARF Value) in 0.5-2keV ct.cm^2/photon phot;instr.det;em.X-ray.soft double nullable afterglow_fraction Suspected Afterglow Fraction meta.code;instr.det double nullable hb_log_photon_flux Logarithm of Incident Photon Flux in Hard (2-8keV) Band log(photon/cm^2/s) phot.flux;em.X-ray.medium double nullable nominal_exposure Total Exposure Time in Merged Observations s time.duration;obs.exposure double nullable fb_bck_counts Observed 0.5-8keV Counts in Merged Background Regions ct phot;instr.background;em.X-ray int nullable hb_total_counts Observed 2-8keV Counts in Merged Apertures ct phot;em.X-ray.medium short nullable bck_scaling Scaling of Background Extraction meta.code;instr.background double nullable log_nh Gas Column Density cm^-2 phys.columnDensity double nullable lii Galactic Longitude degree pos.galactic.lon double nullable single_ks_prob Smallest p-Value for the No-Variability Null Hypothesis within a Single Obs. stat.probability double nullable log_nh_sys_err 1-Sigma Systematic Uncertainty for the Column Density cm^-2 stat.error.sys;phys.columnDensity double nullable sb_prob_no_src The p-Value for the No-Source Hypothesis in the Soft (0.5-2keV) Band stat.probability double nullable sb_counts_pos_err 1-Sigma Upper Error on Net 0.5-2keV Counts ct stat.error;phot;em.X-ray.soft double nullable hb_median_energy Median 2-8keV Energy, Observed Spectrum keV phys.energy double nullable hb_flux Absorption-Corrected 2-8keV X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray.medium double nullable fb_arf_value Mean Effective Area (ARF Value) in 0.5-8keV ct.cm^2/photon phot;instr.det;em.X-ray double nullable frac_expo_discard Fraction of Exposure Discarded in Merge meta.code;time.duration;obs.exposure double nullable internal_name Source Designation Used within the Project meta.id char nullable merged_ks_prob Smallest p-Value for the No-Variability Null Hypothesis over Merged Observations stat.probability double nullable fb_log_photon_flux Logarithm of Incident Photon Flux in Total (0.5-8keV) Band log(photon/cm^2/s) phot.flux;em.X-ray double nullable hb_arf_value Mean Effective Area (ARF Value) in 2-8keV ct.cm^2/photon phot;instr.det;em.X-ray.medium double nullable aperture_area Average Aperture Area for Merged Observations in (0.492 arcsec)^2 Units pixel meta.code;phys.angArea double nullable bii Galactic Latitude degree pos.galactic.lat double nullable fb_obs_flux Observed 0.5-8keV X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable sb_log_photon_flux Logarithm of Incident Photon Flux in Soft (0.5-2keV) Band log(photon/cm^2/s) phot.flux;em.X-ray.soft double nullable hb_counts Net 2-8keV Counts in Merged Apertures ct phot;em.X-ray.medium double nullable hb_counts_pos_err 1-Sigma Upper Error on Net 2-8keV Counts ct stat.error;phot;em.X-ray.medium double nullable fb_total_counts Observed 0.5-8keV Counts in Merged Apertures ct phot;em.X-ray int nullable num_obs_merged Number of Observations Merged to Estimate Photometry Properties meta.number;obs short nullable log_nh_stat_err 1-Sigma Statistical Uncertainty for the Column Density cm^-2 stat.error;phys.columnDensity double nullable psf_fraction Average PSF Fraction at 1.5 keV for Merged Observations instr.det.psf double nullable hb_prob_no_src The p-Value for the No-Source Hypothesis in the Hard (2-8keV) Band stat.probability double nullable off_axis_max Largest Value of the Off-Axis Angle for Merged Observations (Theta) arcmin instr.offset;stat.max double nullable sb_median_energy Median 0.5-2keV Energy, Observed Spectrum keV phys.energy double nullable prob_no_src_min Smallest p-Value for the No-Source Hypothesis in the Full, Soft, and Hard Bands stat.probability;stat.min double nullable off_axis_min Smallest Value of the Off-Axis Angle for Merged Observations (Theta) arcmin instr.offset;stat.min double nullable frac_expo Fraction of Total Exposure Time That Source Was Observed meta.code;time.duration;obs.exposure double nullable sb_counts Net 0.5-2keV Counts in Merged Apertures ct phot;em.X-ray.soft double nullable hb_obs_flux Observed 2-8keV X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray.medium double nullable hb_bck_counts Observed 2-8keV Counts in Merged Background Regions ct phot;instr.background;em.X-ray.medium short nullable error_radius 1-Sigma Uncertainty in Position arcsec stat.error;pos double nullable sb_bck_counts Observed 0.5-2keV Counts in Merged Background Regions ct phot;instr.background;em.X-ray.soft int nullable hb_flux_sys_err 1-Sigma Systematic Uncertainty for the Absorption-Corrected 2-8keV X-Ray Flux erg/s/cm^2 stat.error.sys;phot.flux;em.X-ray.medium double nullable fb_prob_no_src The p-Value for the No-Source Hypothesis in the Full (0.5-8keV) Band stat.probability double nullable pos_algorithm Algorithm Used to Estimate Position meta.code char nullable sb_total_counts Observed 0.5-2keV Counts in Merged Apertures ct phot;em.X-ray.soft int nullable num_obs_extracted Total Number of Observations Extracted meta.number;obs short nullable off_axis Average Off-Axis Angle for Merged Observations arcmin instr.offset double nullable sb_counts_neg_err 1-Sigma Lower Error on Net 0.5-2keV Counts ct stat.error;phot;em.X-ray.soft double nullable hb_flux_stat_err 1-Sigma Statistical Uncertainty for the Absorption-Corrected 2-8keV X-Ray Flux erg/s/cm^2 stat.error;phot.flux;em.X-ray.medium double nullable hb_counts_neg_err 1-Sigma Lower Error on Net 2-8keV Counts ct stat.error;phot;em.X-ray.medium 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