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321. M 33 Deep XMM-Newton Survey X-Ray Source Catalog
ID:
ivo://nasa.heasarc/m33deepxmm
Title:
M 33 Deep XMM-Newton Survey X-Ray Source Catalog
Short Name:
M33DEEPXMM
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The authors have obtained a deep 8-field XMM-Newton mosaic of M33 covering the galaxy out to the D<sub>25</sub> isophote and beyond to a limiting 0.2-4.5 keV unabsorbed flux of 5 x 10<sup>-16</sup> erg cm<sup>-2</sup> s<sup>-1</sup> (L > 4 x 10<sup>34</sup> erg s<sup>-1</sup> at the 817 kpc distance of M33). These data allow complete coverage of the galaxy with high sensitivity to soft sources such as diffuse hot gas and supernova remnants (SNRs). In the reference paper, the authors describe the methods they used to identify and characterize 1296 point sources in the 8 fields. They compare their resulting source catalog to the literature, note variable sources, construct hardness ratios, classify soft sources, analyze the source density profile, and measure the X-ray luminosity function (XLF). As a result of the large effective area of XMM-Newton below 1 keV, the survey contains many new soft X-ray sources. The radial source density profile and XLF for the sources suggest that only ~15% of the 391 bright sources with L > 3.6 x 10<sup>35</sup> erg s<sup>-1</sup> are likely to be associated with M33, and more than a third of these are known SNRs. The log(N)-log(S) distribution, when corrected for background contamination, is a relatively flat power law with a differential index of 1.5, which suggests that many of the other M33 sources may be high-mass X-ray binaries. Finally, the authors note the discovery of an interesting new transient X-ray source, which they are unable to classify. The list of XMM-Newton observations used for this survey is given in Table 1 of the reference paper. The data reduction and source detection techniques are described in Section 3 of this same reference. The unabsorbed energy conversion factors (ECF) values for different energy bands and instruments that were used in this paper are as follows (the units are 10<sup>11</sup> counts cm<sup>2</sup> erg<sup>-1</sup>): <pre> HEASARC Energy Band MOS1 MOS2 PN band prefix (keV) Med Filter Med Filter Thin Filter sb0_ 0.2-0.5 0.5009 0.4974 2.7709 sb1_ 0.5-1.0 1.2736 1.2808 6.006 mb_ 1.0-2.0 1.8664 1.8681 5.4819 hb_ 2.0-4.5 0.7266 0.7307 1.9276 fb_ 0.2-4.5 </pre> This table was created by the HEASARC in July 2015 based on an electronic version of Table 3 of the reference paper, the list of XMM-Newton X-ray point sources detected in a deep 8-field mosaic of M33, which was obtained from the ApJS web site. This is a service provided by NASA HEASARC .
322. M 31 Disk Chandra PHAT Survey: HST-Derived Star Formation History
ID:
ivo://nasa.heasarc/m31phatsfh
Title:
M 31 Disk Chandra PHAT Survey: HST-Derived Star Formation History
Short Name:
M31PHATSFH
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". These data are available at <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO</a>. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. This table presents the star formation histories for a subset of sources in the <a href="/W3Browse/chandra/m31phatcxo.html">M31PHATCXO catalog</a>. About one-third of the point sources are not physically associated with a young population, and are therefore more likely to be background galaxies. For the 40 point-like counterpart candidates associated with young populations, the authors find that their age distribution has two peaks at 15-20Myr and 40-50Myr. Considering only the 8 counterpart candidates with typical high-mass main-sequence optical star colors, their age distribution peaks mimic those of the sample of 40. Finally, the authors find that intrinsic faintness, and not extinction, is the main limitation for finding further counterpart candidates. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50 ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table7.dat. This is a service provided by NASA HEASARC .
323. M 31 Disk Chandra PHAT Survey: X-Ray Source Catalog
ID:
ivo://nasa.heasarc/m31phatcxo
Title:
M 31 Disk Chandra PHAT Survey: X-Ray Source Catalog
Short Name:
M31PHATCXO
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The X-ray source populations within galaxies are typically difficult to identify and classify with X-ray data alone. The authors break through this barrier by combining deep new Chandra ACIS-I observations with extensive Hubble Space Telescope (HST) imaging from the Panchromatic Hubble Andromeda Treasury (PHAT) of the M 31 disk. They detect 373 X-ray sources down to 0.35-8.0keV flux of 10<sup>-15</sup>erg/cm<sup>-2</sup>/s over 0.4deg<sup>2</sup>, 170 of which are reported for the first time. The authors identify optical counterpart candidates for 188 of the 373 sources, after using the HST data to correct the absolute astrometry of our Chandra imaging to 0.1". While 58 of these 188 are associated with point sources potentially in M 31, over half (107) of the counterpart candidates are extended background galaxies, 5 are star clusters, 12 are foreground stars, and 6 are supernova remnants. Sources with no clear counterpart candidate are most likely to be undetected background galaxies and low-mass X-ray binaries in M 31. The hardest sources in the 1-8keV band tend to be matched to background galaxies. The 58 point sources that are not consistent with foreground stars are bright enough that they could be high-mass stars in M 31; however, all but 8 have optical colors inconsistent with single stars, suggesting that many could be background galaxies or binary counterparts. For point-like counterparts, the authors examine the star formation history of the surrounding stellar populations to look for a young component that could be associated with a high-mass X-ray binary. The associated star formation histories for sources in the catalog are available in the linked table <a href="/W3Browse/chandra/m31phatsfh.html">M31PHATSFH</a>. In 2015 October, the authors observed the Panchromatic Hubble Andromeda Treasury (PHAT) footprint with Chandra with 7 pointings. The footprints are overlaid on a GALEX NUV image of M 31, along with the corresponding HST coverage, in Figure 1 of the reference paper. At each pointing they observed for about 50ks in VF mode (Chandra ObsID 17008 to 17014 spanning 2015 Oct 06 to 2015 Oct 26). This table was created by the HEASARC in April 2020 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/239/13">CDS Catalog J/ApJS/239/13</a> file table4.dat and table6.dat. This is a service provided by NASA HEASARC .
324. M 16 (Eagle Nebula) Chandra X-Ray Point Source Catalog
ID:
ivo://nasa.heasarc/m16cxo
Title:
M 16 (Eagle Nebula) Chandra X-Ray Point Source Catalog
Short Name:
M16CXO
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
Mechanisms regulating the origin of X-rays in young stellar objects and the correlation with their evolutionary stage are under debate. Studies of the X-ray properties in young clusters allow us to understand these mechanisms. One ideal target for this analysis is the Eagle Nebula (M 16), with its central cluster NGC 6611. At 1750 pc from the Sun, it harbors 93 OB stars, together with a population of low-mass stars from embedded protostars to disk-less Class III objects, with age <= 3 Myr. The authors study an archival 78 ks Chandra/ACIS-I observation of NGC 6611 and two new 80-ks observations of the outer region of M 16, one centered on the Column V and the other on a region of the molecular cloud with ongoing star formation. They detect 1755 point sources with 1183 candidate cluster members (219 disk-bearing and 964 disk-less), studying the global X-ray properties of M 16 and comparing them with those of the Orion Nebula Cluster. The authors also compare the level of X-ray emission of Class II and Class III stars and analyze the X-ray spectral properties of OB stars. Their study supports the lower level of X-ray activity for the disk-bearing stars with respect to the disk-less members. The X-ray luminosity function (XLF) of M 16 is similar to that of Orion, supporting the universality of the XLF in young clusters. Eighty-five percent of the O-type stars of NGC 6611 have been detected in X-rays. With only one possible exception, they show soft spectra with no hard components, indicating that mechanisms for the production of hard X-ray emission in O stars are not operating in NGC 6611. The determination of the absorption corrected X-ray luminosity (L<sub>X</sub>), as well as the plasma temperature (kT) and hydrogen column density (N<sub>H</sub>), requires the analysis of the X-ray spectra. The authors fit the observed spectra with thermal plasma (with both one and two temperatures) and power-law models. They use the APEC ionization-equilibrium thermal plasma code, assuming the sub-solar elemental abundances of Maggio et al. (2007, APJ, 660, 1462). The absorption was treated using the WABS model. The one-temperature (1T) thermal model was applied to all the sources with more than 25 counts, while the two-temperature (2T) thermal model was applied to each source with more than 80 counts. The power-law model has been applied to those sources with hard spectra for which the best-fit thermal model predicts a plasma temperature kT > 5 keV. When more than one model has been used for a given source, the authors chose the best model by the chi-squared probability and visual inspection of the spectrum. This table contains a description of the X-ray properties of 1754 sources (one less than stated in the abstract of the reference paper) derived from three Chandra/ACIS-I observations, together with a source classification based on the optical and infrared properties of each source. Data come from three ACIS-I observations (central or 'c', east or 'e', and north-east or 'ne') and many values are not averaged but presented for each observation as indicated by the parameter prefixes 'c_', 'e_', and 'ne_', respectively. Source detection has been performed with PWDetect, adopting a threshold corresponding to 10 spurious detections. The HEASARC eliminated the 3 parameters describing the plasma temperature of the second spectral component and its associated negative and positive errors for sources in the north-east observation, as these were blank for all entries in the original table as obtained from the CDS. This table was created by the HEASARC in March 2013 based on the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/753/117">CDS Catalog J/ApJ/753/117</a> file xraycat.dat. Some of the values for the alt_name parameter in the HEASARC's implementation of this table were corrected in April 2018. This is a service provided by NASA HEASARC .
325. Merged Catalog of Reflection Nebulae
ID:
ivo://nasa.heasarc/refnebulae
Title:
Merged Catalog of Reflection Nebulae
Short Name:
REFNEBULAE
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
Several catalogs of reflection nebulae have been merged to create a uniform catalog of 913 objects. It contains revised coordinates, cross-identifications of nebulae and stars, as well as identifications with IRAS point sources. The HEASARC has endeavored to render all identifications of the nebulae in the various catalogs according to the styles recommended by the Dictionary of Nomenclature of Celestial Objects. This table was created by the HEASARC in October 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/A+A/399/141">CDS Catalog J/A+A/399/141</a> file table1.dat. This is a service provided by NASA HEASARC .
326. Midcourse Space Experiment (MSX) Point Source Catalog, V2.3
ID:
ivo://nasa.heasarc/msxpsc
Title:
Midcourse Space Experiment (MSX) Point Source Catalog, V2.3
Short Name:
MSX
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the main catalog from Version 2.3 of the Midcourse Space Experiment (MSX) Point Source Catalog (PSC), which supersedes the previous version (1.2) that was released in 1999, and contains 100,000 more sources than the latter. The MSX PSC main catalog used to create this Browse table contains all the sources found in the Galactic Plane survey, and the primary high-latitude regions (the IRAS gaps regions, and the Large Magellanic Cloud). Note that this HEASARC table does not contain the MSX PSC supplementary catalogs, viz. the singleton catalog, the low-reliability catalog, or the minicatalogs for 19 selected regions. The principal objective of the astronomy experiments onboard the MSX satellite was to complete the census of the mid-infrared (4.2-25 micron or um) sky: namely, the areas missed by the IRAS mission (about 4% of the sky was not surveyed by IRAS), and the Galactic Plane (where the sensitivity of IRAS was degraded by confusion noise in regions of high source densities or of structured extended emission). The photometry is based on co-added image plates, as opposed to single-scan data, which results in improved sensitivity and hence reliability in the fluxes. Comparison with Tycho-2 positions indicates that the astrometric accuracy of the new catalog is more than 1" better than that in Version 1.2. The infrared instrument on MSX was named SPIRIT III; it was a 35-cm clear aperture off-axis telescope with five line scanned infrared focal-plane arrays of 18.3 arcseconds square pixels, with a high sensitivity (0.1 Jy at 8.3 um). The filter characteristics of the 6 spectral bands B1, B2, A, C, D and E are summarized below, where all wavelengths are in micron (µm): <pre> Band Center FWHM Points ---------------------------- B1 4.29 um 4.22 - 4.36 um B2 4.35 4.24 - 4.45 A 8.28 6.8 - 10.8 C 12.13 11.1 - 13.2 D 14.65 13.5 - 15.9 E 21.34 18.2 - 25.1 </pre> The MSX catalog names of the sources have been defined according to International Astronomical Union (IAU) conventions with a unique identifier combined with the position of the source. In this case, the MSX PSC V2.3 sources are named using the convention MSX6C GLLL.llll+/-BB.bbbb, where MSX6C denotes that this is MSX data run using Version 6.0 of the CONVERT software, and GLLL.llll+/-BB.bbbb gives the Galactic coordinates of the source. This database table was first created by the HEASARC in November 2002 and then updated in April 2005, based on the 11-Dec-2003 version of the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/V/114">CDS Catalog V/114</a> (specifically, the files gb_gt6.dat, gp_m05m2.dat, gp_m2m6.dat, gp_p05p2.dat, gp_p2p6.dat, and gp_pm05.dat which comprise the main catalog). This is a service provided by NASA HEASARC .
327. Midcourse Space Experiment (MSX) Ultraviolet Point Source Catalog
ID:
ivo://nasa.heasarc/msxuvpsc
Title:
Midcourse Space Experiment (MSX) Ultraviolet Point Source Catalog
Short Name:
MSXUVPSC
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Midcourse Space Experiment (MSX) Ultraviolet Point Source Catalog contains 47,283 point sources (the HEASARC notes that there actually 47,318 sources in this version of the table, 35 more than this number) from a set of 201 observations that surveyed approximately half the sky and from a set of 32 pointed observations toward specific targets. For each source, the catalog provides the position, UV magnitude and uncertainty in at least one of six filters, and, where possible, an identification of a nearby source from the SIMBAD database. If a nearby source is identified, its proximity to the MSX source, and if known, the spectral type and the B and V magnitudes of the SIMBAD object are also provided. There were 11,565 matches between MSX and SIMBAD objects (the HEASARC notes that there actually 11,662 matches in this version of the table, 97 more than this number), and the authors estimate the number of false identifications to be about 3%. The limiting fluxes differ from filter to filter, and range from 10<sup>-16</sup> erg/s/cm<sup>2</sup>/Angstrom for IUN4 to 7.8 x 10<sup>-12</sup> erg/s/cm<sup>2</sup>/Angstrom for IUW3. Because of variations among the observation sets, the catalog is not complete to the limiting magnitudes for the filters. The UV instrument on MSX was named UVISI (Mill et al., 1994, Journal of Spacecraft and Rockets, 31, 900 (1994JSpRo..31..900M in ADS); Carbary et al., 1994, Applied Optics, 33, 4201 (1994ApOpt..33.4201C in ADS)). The fields-of-view for the narrow-field and wide-field UV imagers were 1.46 x 1.19 degrees (detector pixels of 20.6" x 17.5") and 13.4 x 9.2 degrees (detector pixels of 3.12' x 2.27'), respectively. Four filters were used with the narrow-field imager (IUN) with effective wavelengths centered at 2480 Angstrom (IUN3), 2310 Angstrom (IUN4), 2230 Angstrom (IUN5), and 2930 Angstrom (IUN6). Two filters were used with the wide-field imager (IUW) and centered at 1320 Angstrom (IUW3) and 1560 Angstrom (IUW6). The HEASARC has removed from this table the parameter describing the objects' magnitude in the IUN5 filter as all of the sources had null values for this parameter. The CDS had previously made the following modifications compared to the version of the catalog as published in the reference paper: <pre> (1) The angular distances to the SIMBAD object (column "AngDist" of file catal.dat, called 'Offset' in this HEASARC table) was recomputed at CDS, the original values looking suspect. (2) In the course of this modification, 17 SIMBAD IDs were removed due to a large offset, most likely due to a sign error in the interpretation of SIMBAD's declination for IDs: 003341+001712 063054+004539 063211+005630 063754+003151 133358+001928 142557+003939 144541+002439 155701+004808 162743+004620 185855+003355 191033+004132 193004+005316 194525+001239 195040+004101 195717+001959 202844+005149 234324+000729 </pre> This table was created by the HEASARC in April 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/II/269">CDS Catalog II/269</a> file catal.dat. This is a service provided by NASA HEASARC .
328. Milky Way Molecular Clouds from CO Measurements
ID:
ivo://nasa.heasarc/mwmc
Title:
Milky Way Molecular Clouds from CO Measurements
Short Name:
MWMC
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This study presents a catalog of 8107 molecular clouds that covers the entire Galactic plane and includes 98% of the <sup>12</sup>CO emission observed within b +/- 5 deg. The catalog was produced using a hierarchical cluster identification method applied to the result of a Gaussian decomposition of the Dame+ (2001ApJ...547..792D) data. The total H<sub>2</sub> mass in the catalog is 1.2 x 10<sup>9</sup> M<sub>sun</sub>, in agreement with previous estimates. The authors find that 30% of the sight lines intersect only a single cloud, with another 25% intersecting only two clouds. The most probable cloud size is R~30pc. In contrast with the general idea, the authors find a rather large range of values of surface densities, Sigma = 2 to 300 M<sub>sun</sub>/pc<sup>2</sup>, and a systematic decrease with increasing Galactic radius, R<sub>gal</sub>. The cloud velocity dispersion and the normalization sigma<sub>0</sub> = sigma<sub>v</sub> / R<sup>1/2</sup> both decrease systematically with R<sub>gal</sub>. When studied over the whole Galactic disk, there is a large dispersion in the line width-size relation and a significantly better correlation between sigma<sub>v</sub> and SigmaR. The normalization of this correlation is constant to better than a factor of two for R<sub>gal</sub> < 20kpc. This relation is used to disentangle the ambiguity between near and far kinematic distances. The authors report a strong variation of the turbulent energy injection rate. In the outer Galaxy it may be maintained by accretion through the disk and/or onto the clouds, but neither source can drive the 100 times higher cloud-averaged injection rate in the inner Galaxy. The data set used in this catalog come from that of Dame+ (2001ApJ...547..792D). Those authors combined observations obtained over a period of 20 yr with two telescopes, one in the north (first located in New York City and then moved to Cambridge, Massachusetts) and one in the south (Cerro Tololo, Chile). These 1.2m telescopes have an angular resolution of ~8.5' at 115GHz, the frequency of the <sup>12</sup>CO 1-0 line. For the current study the authors used the data set covering the whole Galactic plane with +/- 5 deg in Galactic latitude. This table was created by the HEASARC in March 2019 based upon the <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/834/57">CDS Catalog J/ApJ/834/57</a> file table1.dat. This is a service provided by NASA HEASARC .
329. Million Quasars Catalog (MILLIQUAS), Version 8 (2 August 2023)
ID:
ivo://nasa.heasarc/milliquas
Title:
Million Quasars Catalog (MILLIQUAS), Version 8 (2 August 2023)
Short Name:
MILLIQUAS
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
This table contains the Million Quasars (MILLIQUAS) Catalog, Version 8 (2 August 2023). It is a compendium of 907,144 type-I QSOs and AGN, largely complete from the literature to 30 June 2023. 66,026 QSO candidates are also included, calculated via radio/X-ray association (including double radio lobes) as being 99% likely to be quasars. Blazars and type-II objects are also included, bringing the total count to 1,021,800. 60.7% of all objects show Gaia-EDR3 astrometry. Low-confidence/quality or questionable objects (so deemed by their researchers) are not included in Milliquas. Additional quality cuts can be applied as detailed in the HMQ paper (Flesch 2015,PASA,32,10). Full QSO/AGN classification is accomplished via spectral lines, yielding a reliable spectroscopic redshift. Two spectral lines are required, or one spectral line refining a compatible photometric redshift. Obscured AGN with redshifts from the hosts only are taken to be type-II objects. Some legacy quasars with neither good spectra nor radio/X-ray association were flagged by Gaia-EDR3 as 5-sigma moving (i.e., stars), and so were removed from Milliquas. All objects are de-duplicated across source catalogs. The author's aim here is to present one unique reliable object per each data row. Two NIQs offset < 2 arcsec can be reported as a single object if within the same host. Lenses are reported as single objects onto the brightest quasar imaged. (Milliquas is not a catalog of lenses.) The contents are relatively simple; each object is shown as one entry with the sky coordinates (of whatever epoch), its original name, object class, red and blue optical magnitudes, PSF class, redshift, the citations for the name and redshift, and up to four radio/X-ray identifiers where applicable. Questions/comments/praise/complaints may be directed to Eric Flesch at eric@flesch.org. If you use this catalog in published research, the author requests that you please cite it. The confirmed quasars of this catalog (to Jan 2015) were published as the Half Million Quasars (HMQ) catalog: Flesch E., 2015,PASA,32,10. Note however that Milliquas uses optical sky data from ASP (2017,PASA,34,25) whereas the HMQ used optical sky data from QORG (2004,A&A,427,387) Appendix A. This table was updated by the HEASARC in July 2023 based on a machine-readable catalog obtained from the author's MILLIQUAS website at <a href="https://quasars.org/milliquas.htm">https://quasars.org/milliquas.htm</a>. <p> This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. <p> This research has made use of the SIMBAD database and CDS cross-match service (to obtain Gaia-EDR3 and Pan-STARRS photometry) provided by CDS, Strasbourg, France. <a href="https://simbad.cds.unistra.fr/simbad">https://simbad.cds.unistra.fr/simbad</a> This is a service provided by NASA HEASARC .
330. Millions of Optical Radio/X-Ray (MORX) Associations Catalog, Version 2
ID:
ivo://nasa.heasarc/morx
Title:
Millions of Optical Radio/X-Ray (MORX) Associations Catalog, Version 2
Short Name:
MORX
Date:
18 Apr 2025
Publisher:
NASA/GSFC HEASARC
Description:
The Millions of Optical Radio/X-ray Associations (MORX) catalog combines all of the largest published optical, radio, and X-ray sky catalogs to find probable radio/X-ray associations with optical objects, plus double radio lobes, using uniform processing against all input data. This catalog contains 3,115,575 optical objects. Each object has optical coordinates (of the epoch of its photometry), its original name (if any), object class, red and blue optical magnitudes, PSF class, redshift (if any), the citations for the name and redshift, and the likelihoods of the radio/X-ray associations and that the object (if unclassified) should be a QSO, galaxy, or star. Each object may have up to four X-ray identifiers, up to five radio identifiers, and up to two double radio lobe identifiers. MORX is a compendium of optical objects which are calculated as being associated with Chandra, XMM-Newton, Swift, or ROSAT X-ray sources, or with NVSS, FIRST, VLASS, LoTSS, RACS, or SUMSS radio sources or double radio lobes. All have likelihoods in the range of 40-100% confidence in their associations. The counts of the associations for this main sample are as follows: <pre> Optical objects (rows in this catalog) - 3,115,575 Chandra - 102,652 X-ray associations XMM-Newton - 263,649 X-ray associations Swift - 120,647 X-ray associations ROSAT - 31,750 X-ray associations XMM Slew - 11,428 X-ray associations VLASS - 439,283 core radio associations, plus 15,763 double radio lobes(*). LoTSS - 1,804,886 core radio associations, plus 73,142 double radio lobes. RACS - 582,668 core radio associations, plus 12,009 double radio lobes. FIRST - 275,552 core radio associations, plus 9000 double radio lobes. NVSS - 316,039 core radio associations, plus 675 double radio lobes. SUMSS - 47,549 core radio associations, plus 42 double radio lobes. </pre> (*) Lobe pairs are presented once only, so not from multiple radio surveys. MORX and <a href="/W3Browse/all/milliquas.html">Milliquas</a> are extracted from the same master data pool. All data quality rules pertaining to Milliquas also hold for MORX. The radio/X-ray source prefixes, and their source catalog home pages that are cited in this table, are as follows: <pre> FIRST: VLA FIRST survey, 13Jun05 version, <a href="https://sundog.stsci.edu">https://sundog.stsci.edu</a> VLA (abbrev of VLASS1QLCIR): VLASS Quick Look, <a href="https://cirada.ca/catalogues">https://cirada.ca/catalogues</a> RACS: Rapid ASKAP Continuum Survey, 2021,PASA,38,58, <a href="https://research.csiro.au/racs/">https://research.csiro.au/racs/</a>, main source file RACD: RACS as above, but from their main detection ("Gaussian") file ILT: LoTSS-DR2 (LOFAR Two-metre Sky Survey), 2022,A&A,659,A1, <a href="https://lofar-surveys.org/">https://lofar-surveys.org/</a>, main source catalog ILD: LoTSS-DR2 as above, but from their main detection ("Gaussian") file NVSS: NRAO VLA sky survey, <a href="https://www.cv.nrao.edu/nvss">https://www.cv.nrao.edu/nvss</a> SUMSS: Sydney U. Molonglo, <a href="http://www.astrop.physics.usyd.edu.au/sumsscat/">http://www.astrop.physics.usyd.edu.au/sumsscat/</a> MGPS: Molonglo galactic plane, www.astrop.physics.usyd.edu.au/mgpscat/ 1RXH: ROSAT HRI (high resolution), <a href="https://cdsarc.cds.unistra.fr/cat/?IX/28A">https://cdsarc.cds.unistra.fr/cat/?IX/28A</a> 2RXP: ROSAT PSPC (proportional), <a href="https://cdsarc.cds.unistra.fr/cat/?IX/30">https://cdsarc.cds.unistra.fr/cat/?IX/30</a> 2RXF: <a href="https://heasarc.gsfc.nasa.gov/W3Browse/rosat/rospspcftot.html">https://heasarc.gsfc.nasa.gov/W3Browse/rosat/rospspcftot.html</a> 1WGA: White, Giommi & Angelini, <a href="https://heasarc.gsfc.nasa.gov/wgacat/">https://heasarc.gsfc.nasa.gov/wgacat/</a> CXOG: Chandra ACIS source catalog, Wang S. et al., 2016,ApJS,224,40 CXO: Chandra Source Catalog v1.1, <a href="https://asc.harvard.edu/csc1/">https://asc.harvard.edu/csc1/</a> 2CXO: Chandra Source Catalog v2.0, <a href="https://asc.harvard.edu/csc2/">https://asc.harvard.edu/csc2/</a> CXOX: XAssist Chandra, <a href="https://asd.gsfc.nasa.gov/xassist/pipeline4/chandra/">https://asd.gsfc.nasa.gov/xassist/pipeline4/chandra/</a> 2XMM/2XMMi: XMM-Newton DR3, <a href="https://cdsarc.cds.unistra.fr/cat/?IX/41">https://cdsarc.cds.unistra.fr/cat/?IX/41</a> 4XMM: XMM-Newton DR13, <a href="https://www.cosmos.esa.int/web/xmm-newton/xsa">https://www.cosmos.esa.int/web/xmm-newton/xsa</a> XMMSL: XMM-Newton Slew Survey Release 2.0, same attribution as 4XMM XMMX: XAssist XMM-Newton, <a href="https://asd.gsfc.nasa.gov/xassist/pipeline5/xmm/">https://asd.gsfc.nasa.gov/xassist/pipeline5/xmm/</a> LSXPS: Swift X-ray Point Sources, <a href="https://www.swift.ac.uk/LSXPS">https://www.swift.ac.uk/LSXPS</a> (01July23) </pre> RASS (ROSAT All-Sky Survey) is not included as its low resolution is not usable in isolation. Optical field solutions are calculated from the raw source positions of all these catalogs (except 2CXO) as described in the author's MORX v1 paper, 2016,PASA,33,52. This table was originally ingested by the HEASARC in May 2017. It was last updated in July 2023 to version 2 based upon the data file downloaded from the author's website at <a href="https://quasars.org/morx.htm">https://quasars.org/morx.htm</a>. <p> This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory,California Institute of Technology, under contract with the National Aeronautics and Space Administration. <p> This research has made use of the SIMBAD database and CDS cross-match service to obtain Gaia-EDR3 and Pan-STARRS photometry provided by CDS, Strasbourg, France. This is a service provided by NASA HEASARC .