L1641IOXMM ivo://nasa.heasarc/l1641ioxmm NASA/GSFC HEASARC Pillitteri et al. 2026-10-09 NASA/GSFC HEASARC help desk heasarc-vo at athena.gsfc.nasa.gov Survey Source This table contains results from an XMM-Newton and Spitzer survey of the part of the Orion A cloud south of the Orion Nebula, the 'Survey of Orion A with XMM-Newton and Spitzer (SOXS)'. The goal of SOXS is to detect the relatively bright X-ray sources in the Orion A cloud and complete the census of more evolved YSOs in this region. These stars represent a sample of cloud members chosen with minimal a priori bias toward their IR properties. This XMM-Newton survey includes the Lynds 1641 (L1641) dark cloud, a region of the Orion A cloud with very few massive stars and hence a relatively low ambient UV flux, and the region around the O9 III star iota Orionis. In addition to proprietary data, the authors used archival XMM data of the Orion Nebula Cluster (ONC) to extend their analysis to a major fraction of the Orion A cloud. They have detected 1060 X-ray sources with more than 4.5-sigma significance in L1641 and the iota Ori region. About 94% of the sources have Two Micron All Sky Survey (2MASS) and Spitzer counterparts, 204 and 23 being Class II and Class I or protostar objects, respectively. In addition, the authors have identified 489 X-ray sources as counterparts to Class III candidates, given they are bright in X-rays and appear as normal photospheres at mid-IR wavelengths. The remaining 205 X-ray sources are likely distant active galactic nuclei (AGN) or other galactic sources not related to Orion A. The authors find that Class III candidates appear more concentrated in two main clusters in L1641. The first cluster of Class III stars is found toward the northern part of L1641, concentrated around iota Ori. The stars in this cluster are more evolved than those in the Orion Nebula. The authors estimate a distance of 300-320 pc for this cluster showing that it is in the foreground of the Orion A cloud. Another cluster rich in Class III stars is located in L1641 South and appears to be a slightly older cluster embedded in the Orion A cloud. Furthermore, other evolved Class III stars are found north of the ONC toward NGC 1977. The SOXS survey is composed of seven specifically proposed ~ 50 ks XMM-Newton fields, south of the ONC, to which the authors added four archival fields in the same region. The archival fields are centered on iota Orionis, V380 Ori, and V883 Ori, respectively (see Fig. 1 and Table 1 of the reference paper for more details of the X-ray observations). This HEASARC table contains the contents of Table 2 (1060 X-ray detected sources in the fields S1 - S10 listed in Table 1 of the reference paper), Table 3 (best-fit spectral parameters for the 232 brightest of these X-ray sources) and Table 4 (list of 1041 IR counterparts to the X-ray sources) from the reference paper. Some X-ray sources have no identified counterparts (16 of them in fact lie outside of the FOV of the Spitzer observations), most have a single counterpart, and a small number have 2 or even 3 IR counterparts within the 5 arcseconds matching radius used. For X-ray sources with more than 1 IR counterpart, we have added entries for the additional counterparts (71 in total), repeating the X-ray information in such cases. Thus, this HEASARC table contains 1131 (1060 + 71) entries corresponding to the 1060 X-ray source detections. To make its contents easier to visualize, the HEASARC has added a a parameter ir_match which lists the counterpart number for the entry: If there is no identified IR counterpart, ir_match is set to 0, for the first listed IR counterpart to 1, for the second and third, to 2 and 3, respectively. Thus, if the user wants to reduce the table back to a pure list of X-ray sources and their primary IR counterparts, they should search the table selecting ir_match < 2. This table was created by the HEASARC in August 2013 based on the electronic versions of Tables 2 and 3 from the original reference paper (2013ApJ...768...99P) and Table 4 from the erratum (2013ApJ...773...80P), which were all obtained from the ApJ web site. This is a service provided by NASA HEASARC . 2013ApJ...768...99P https://heasarc.gsfc.nasa.gov/W3Browse/all/l1641ioxmm.html Catalog Research served-by HEASARC TAP https://heasarc.gsfc.nasa.gov/xamin/vo/cone?showoffsets&table=l1641ioxmm& GET text/xml 180 99999 true 85.67708333 -8.80366667 0.0166666666666667 https://heasarc.gsfc.nasa.gov/xamin/vo/tap https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/getvotable.pl?name=l1641ioxmm GET text/xml https://heasarc.gsfc.nasa.gov/cgi-bin/W3Browse/w3query.pl?tablehead=name=heasarc_l1641ioxmm&Action=More+Options&Action=Parameter+Search&ConeAdd=1 XMM-NEWTON 0.0166666666666667 Radio public l1641ioxmm Lynds 1641 and iota Ori Region XMM-Newton X-Ray Point Source Cat source_number Sequential Identification Number for Each Source in Catalog meta.id;src short nullable 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 off_axis Off-Axis Distance arcmin instr.offset double nullable count_rate Count (0.3-8keV) Rate Scaled to MOS Sensitivity ct/s phot.count;em.X-ray double nullable flux The 0.3-8 keV X-Ray Flux erg/s/cm^2 phot.flux;em.X-ray double nullable exposure Sum of Exposure Times from EPIC Cameras s time.duration;obs.exposure double nullable jmag 2MASS J Band Magnitude mag phot.mag;em.IR.J double nullable irac_3p6_um_mag Spitzer/IRAC 3.6-Micron Band Magnitude mag phot.mag;em.IR.3-4um 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 ir_match Sequential Number Designating a Matching Counterpart in the Infrared meta.id.cross short nullable apec_abundance Global Abundance phys.abund;stat.fit.param double nullable count_rate_error Uncertainty in Count Rate ct/s stat.error;phot.count;em.X-ray double nullable apec_kt_1 First Component kT Value keV phys.temperature;stat.fit.param double nullable ir_xray_offset Angular Separation Between X-Ray and IR Positions arcsec pos.angDistance;em.IR;em.X-ray double nullable apec_kt_1_error Uncertainty in First Component kT Value keV stat.error;phys.temperature;stat.fit.param double nullable ra_ir Right Ascension of Infrared Source degree pos.eq.ra double nullable lii Galactic Longitude degree pos.galactic.lon double nullable nh Hydrogen Column Absorption cm^-2 phys.columnDensity double nullable irac_4p5_um_mag Spitzer/IRAC 4.5-Micron Band Magnitude mag phot.mag;em.IR.4-8um double nullable ir_spectrum_flag Flag [TF] Indicates Class 0/I/Flat-Spectrum Object meta.code;spect char nullable mips_24_um_mag Spitzer/MIPS 24-Micron Band Magnitude mag phot.mag;em.IR.15-30um double nullable irac_8p0_um_mag Spitzer/IRAC 8.0-Micron Band Magnitude mag phot.mag;em.IR.4-8um double nullable apec_norm_2 Second Component Normalization cm^-5 stat.fit.param double nullable dof Degrees of Freedom stat.fit.dof short nullable counts_error Uncertainty in Net Total Counts ct stat.error;phot;em.X-ray int nullable apec_kt_2 Second Component kT Value keV phys.temperature;stat.fit.param double nullable reduced_chi_squared Reduced Chi^2 of Model stat.fit.chi2 double nullable obsid XMM-Newton Observation Identifier meta.id;obs char nullable counts Net Total (MOS1+MOS2+PN) 0.3-8keV Counts ct phot;em.X-ray int nullable bii Galactic Latitude degree pos.galactic.lat double nullable class_3_status_flag Flag [TF] Indicates Class III Candidate Status meta.code;src.class char nullable class_2_status_flag Flag [TF] Indicates Class II Candidate Status meta.code;src.class char nullable irac_5p8_um_mag Spitzer/IRAC 5.8-Micron Band Magnitude mag phot.mag;em.IR.4-8um double nullable ks_mag 2MASS K_s Band Magnitude mag phot.mag;em.IR.K double nullable apec_kt_2_error Uncertainty in Second Component kT Value keV stat.error;phys.temperature;stat.fit.param double nullable dec_ir Declination of Infrared Source degree pos.eq.dec double nullable spectral_model Spectral Model Descriptor meta.code;spect;meta.modelled char nullable hmag 2MASS H Band Magnitude mag phot.mag;em.IR.H double nullable nh_error Uncertainty in NH cm^-2 stat.error;phys.columnDensity double nullable apec_norm_2_error Uncertainty in Second Component Normalization cm^-5 stat.error;stat.fit.param double nullable apec_norm_1_error Uncertainty in First Component Normalization cm^-5 stat.error;stat.fit.param double nullable apec_norm_1 First Component Normalization cm^-5 stat.fit.param double nullable