- ID:
- ivo://nasa.heasarc/egrcat
- Title:
- CGRO/EGRET Revised Catalog of Gamma-Ray Sources
- Short Name:
- EGRCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The CGRO/EGRET Revised Catalog of Gamma-Ray Sources (EGR) is a catalog of point gamma-ray sources detected by the EGRET detector on the Compton Gamma Ray Observatory. The authors used the entire EGRET gamma-ray dataset of reprocessed photons at energies above 100 MeV and new Galactic interstellar emission models based on CO, H I, dark gas, and interstellar radiation field data. Two different assumptions are used to describe the cosmic-ray distribution in the Galaxy to analyse the systematic uncertainties in source detection and characterization. The authors applied a 2-dimensional maximum-likelihood detection method similar to that used to analyze the 3rd EGRET catalogue (3EG: Hartman et al. 1999, ApJS, 123, 79, available as the EGRET3 Catalog in Browse). The revised EGRET catalog (EGR) lists 188 sources, 14 of which are marked as confused, in contrast to the 271 entries of the 3rd EGRET (3EG) catalog. The authors do not detect 107 sources discovered previously because additional structure is present in the interstellar background. The vast majority of them were unidentified and marked as possibly extended or confused in the 3EG catalog. In particular, the authors do not confirm most of the 3EG sources associated with the local clouds of the Gould Belt. Alternatively, they have found 30 new sources that have no 3EG counterpart. The new error circles for the confirmed 3EG sources largely overlap the previous ones, but several counterparts of particular interest discussed before, such as Sgr A*, radio galaxies, and several microquasars are now found outside the error circles. The authors cross-correlated the source positions with a large number of radio pulsars, pulsar wind nebulae, supernova remnants, OB associations, blazars and flat radiosources and they found a surprising large number of sources (87) at all latitudes that have no counterpart among the potential gamma-ray emitters. Sources found within a radius of 1.5 PSF FWHM of a very bright source, and/or with very asymmetric TS map contours, are not included in the primary list of EGR sources but are included as EGRc sources herein. The EGRc sources represent significant excesses of photons above the background that may be due to extended sources, or structures not properly modeled in the interstellar emission, or artefacts due to incorrect PSF tails. As noted above, there are 188 sources in this catalog: since there are multiple measurements for these sources corresponding to the various viewing periods, there are 1640 entries in the HEASARC's version of the Revised EGRET Catalog, corresponding to 1512 'observations' of the 174 primary gamma-ray sources plus 128 'observations' of the 14 confused sources. Thus, there are an average of about 9 entries for every gamma-ray source. This table was created by the HEASARC in March 2009 based on the electronic versions of Tables A1 and B1 from the paper, which were obtained from the CDS, their catalog J/A+A/489/849 files egr.dat and egrc.dat. This is a service provided by NASA HEASARC .
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- ID:
- ivo://nasa.heasarc/egret3
- Title:
- CGRO/EGRET Third Source Catalog
- Short Name:
- EGRET
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Third EGRET Catalog of High-Energy Gamma-Ray Sources is based on data obtained by the Energetic Gamma-Ray Experiment Telescope (EGRET) on board the Compton Gamma-Ray Observatory (CGRO) during the period from 1991 April 22 to 1995 October 3, corresponding to GRO Cycles 1, 2, 3, and 4. EGRET is sensitive to photons in the energy range from about 30 MeV to over 20 GeV, the highest energies accessible by the CGRO instruments, and, like COMPTEL, is an imaging instrument. In addition to including more data than the Second EGRET Catalog (2EG, Thompson et al. 1995, ApJS, 101, 259) and its supplement (2EGS, Thompson et al. 1996, ApJS, 107, 227), this catalog uses completely reprocessed data so as to correct a number of mostly minimal errors and problems. The 271 sources (E > 100 MeV) in the catalog include the single 1991 solar flare that was bright enough to detected as a source, the LMC, 5 pulsars, one probable radio galaxy detection (Cen A), and 66 high-confidence identifications of blazars (BL Lac objects, flat-spectrum radio quasars, or unidentified flat-spectrum radio sources). In addition, 27 lower-confidence potential blazar identifications are noted. Finally, the catalog contains 170 sources that are not yet firmly identified with known objects, although potential identifications have been suggested for a number of these. As already noted, there are 271 distinct sources in this catalog: since there are multiple measurements for these sources corresponding to the various viewing periods, there are 5246 entries in the HEASARC's version of the 3rd EGRET Catalog corresponding to the same number of lines in Table 4 of the published version. Thus, there are an average of about 20 entries for every distinct source. Notice that 14 sources reported in the 2nd EGRET Catalog or its supplement do not appear in this 3rd EGRET Catalog: 2EG J0403+3357, 2EG J0426+6618, 2EGS J0500+5902, 2EGS J0552-1026, 2EG J1136-0414, 2EGS J1236-0416, 2EG J1239+0441, 2EG J1314+5151, 2EG J1430+5356, 2EG J1443-6040, 2EG J1631-2845, 2EG J1709-0350, 2EG J1815+2950, and 2EG J2027+1054 due to the fact that the re-analysis of the EGRET data has dropped their statistical significance from just above the catalog threshold to just below it; additional information on these sources is provided in Table 5 of the published version of the 3rd EGRET Catalog. This database table was created by the HEASARC in June 1999, based on a machine-readable version of Table 4 of the 3rd EGRET Source Catalog that was provided by the CGRO Science Support Center (CGROSSC). Slight modifications to the Browse Object Classifications were later made in April 2001. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/osse
- Title:
- CGRO/OSSE Observations
- Short Name:
- OSSE
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table is based on the set of OSSE observation data products available at the HEASARC. The Oriented Scintillation Spectrometer Experiment (OSSE) is one of four experiments on NASA's Compton Gamma Ray Observatory (CGRO) satellite. OSSE was designed to undertake comprehensive gamma-ray observations of astrophysical sources in the 0.05-10 MeV energy range. The instrument also had secondary capabilities for gamma-ray and neutron observations above 10 MeV that are of particular value for solar flare studies. This database table was last updated in August 2005. Some duplicate entries in the table were removed in June 2019. The data in this table was supplied by the CGRO Science Support Center. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/cgroprspec
- Title:
- CGROProposalInfo&Abstracts
- Short Name:
- CGROPRSPEC
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This database table describes the accepted proposals made to the Compton Gamma Ray Observatory (CGRO) project. The data come from both the paper submissions prior to the Remote Proposal Submission (RPS) automatic process, as well as from RPS itself. This database table was created by a cooperative effort of the HEASARC and the Compton Observatory Science Support Center (COSSC). This is a service provided by NASA HEASARC .
145. CGRO Timeline
- ID:
- ivo://nasa.heasarc/cgrotl
- Title:
- CGRO Timeline
- Short Name:
- CGROTL
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The Compton Gamma-Ray Observatory (CGRO) was the second of NASA's Great Observatories. It was launched on April 5, 1991, from Space Shuttle Atlantis. It operated successfully for 9 years, and then was safely de-orbited and re-entered the Earth's atmosphere on June 4, 2000. Compton had four instruments that covered an unprecedented six decades of the electromagnetic spectrum, from 30 keV to 30 GeV. In order of increasing spectral energy coverage, these instruments were the Burst And Transient Source Experiment (BATSE), the Oriented Scintillation Spectrometer Experiment (OSSE), the Imaging Compton Telescope (CompTel), and the Energetic Gamma Ray Experiment Telescope (EGRET). BATSE viewed the full sky, as a transient monitor and is thus not included in this database table of pointed telescope observations. Also, EGRET and CompTel had wide fields of view, about 30 degrees, and, as such, viewed multiple targets per X-axis pointing. OSSE could be slewed (about one axis) independently from the spacecraft, so it typically viewed 2 targets per spacecraft Z-axis orientation, or "viewing period." Viewing periods were typically two weeks long. This database table contains the CGRO observations for Cycles 1 through 9. The Cycle 1 observations for EGRET and COMPTEL were part of the All-Sky Survey with no defined targets. This database table was last updated in November 2001. The information contained therein was provided by the Compton Observatory Science Support Center (COSSC). Galactic coordinates were added to the table by the HEASARC in August 2005. Duplicate entries in the table were removed in June 2019. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chainthcxo
- Title:
- Chamaeleon I North Cloud Chandra X-Ray Point Source Catalog
- Short Name:
- CHAINTHCXO
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Chamaeleon (Cha) I North Cloud Chandra X-Ray point source catalog. Sensitive X-ray imaging surveys provide a new and effective tool to establish the census of pre-main-sequence (PMS) stars in nearby young stellar clusters. A deep Chandra X-Ray Observatory (CXO) observation of PMS stars in the Chamaeleon I North cloud achieved a limiting total-band X-ray luminosity of log L<sub>t</sub> ~ 10<sup>27</sup> ergs/s (0.5 - 8 keV band) in a 0.8 x 0.8 pc<sup>2</sup> region. Of the 107 X-ray sources, 37 are associated with Galactic stars, of which 27 are previously recognized cloud members. These include 3 PMS brown dwarfs: the protostellar brown dwarf ISO 192 has a particularly high level of magnetic activity. Follow-up optical photometry and spectroscopy establish that 9-10 of the Chandra sources are probably magnetically active background stars. No new X-ray-discovered stars were confidently found despite the high sensitivity of the Chandra observation. From these findings, the authors argue that the sample of 27 PMS cloud members in the Chandra field is uncontaminated and complete down to K = 12 or a stellar mass of about 0.1 solar masses. A 16'x 16' region of the Cha I North cloud was observed with the imaging array of the Advanced CCD Imaging Spectrometer (ACIS-I) detector on board the Chandra X-Ray Observatory. The observation took place on 2001 July 2.25-3.04 UT with the detector aimpoint set at 11 10 00.0, -76 35 00 (J2000.0 RA and Declination). The effective exposure was 66.3 ksec. The authors also obtained VI-band CCD images of most of the ACIS field with the 1m telescope and CCD detector at the South African Astronomical Observatory (SAAO) during 2002 February. This table was created by the HEASARC in February 2007 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/614/267">CDS catalog J/ApJ/614/267</a> files table1.dat, table2.dat and table3.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/champhxagn
- Title:
- CHAMP (Chandra Multiwavelength Project) Hard X-Ray Emitting AGN
- Short Name:
- CHAMPHXAGN
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the results from an X-ray and optical analysis of 188 active galactic nuclei (AGN) identified from 497 hard X-ray (observed flux in the (2.0 - 8.0 keV) band > 2.7 x 10<sup>-15</sup> erg/cm<sup>2</sup>/s) sources in 20 Chandra fields (1.5 square degrees) forming part of the Chandra Multiwavelength Project (ChaMP). These medium-depth X-ray observations enable the detection of a representative subset of those sources responsible for the bulk of the 2 - 8 keV cosmic X-ray background. Brighter than the survey's optical spectroscopic limit, the authors achieve a reasonable degree of completeness (77% of X-ray sources with counterparts r' < 22.5 have been classified): broad emission-line AGNs (62%), narrow emission-line galaxies (24%), absorption-line galaxies (7%), stars (5%), or clusters (2%). To construct a pure AGN sample, the authors required the rest-frame 2.0-8.0 keV luminosity (uncorrected for intrinsic absorption) to exceed 10<sup>42</sup> erg s<sup>-1</sup>, thereby excluding any sources that may contain a significant stellar or hot ISM component. The most luminous known star-forming or elliptical galaxies attain at most L<sub>X</sub> = 10<sup>42</sup> erg s<sup>-1</sup>. Since many of the traditional optical AGN signatures are not present in obscured sources, high X-ray luminosity becomes the authors' single discriminant for supermassive black hole accretion. They believe that almost all of the NELGs and ALGs harbor accreting SMBHs based on their X-ray luminosity. They find that 90% of the identified ChaMP sources have luminosities above this threshold. These selection criteria yield a sample of 188 AGNs from 20 Chandra fields with f(2-8 keV) > 2.7 x 10<sup>-15</sup> erg cm<sup>-2</sup> s<sup>-1</sup>, r' < 22.5, and L<sub>X</sub> > 10<sup>42</sup> erg s<sup>-1</sup>. The authors removed five objects identified as clusters based on their extended X-ray emission. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJ/618/123, file table4.dat. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/chesscat
- Title:
- ChaMP Extended Stellar Survey (ChESS) X-Ray Catalog
- Short Name:
- CHESSCAT
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The ChaMP Extended Stellar Survey (ChESS) X-ray catalog contains 348 X-ray-emitting stars identified from correlating the Extended Chandra Multiwavelength Project (ChaMP), a wide-area serendipitous survey based on archival X-ray images, with the Sloan Digital Sky Survey (SDSS). The authors used morphological star/galaxy separation, matching to an SDSS quasar catalog, an optical color-magnitude cut, and X-ray data-quality tests to create this catalog, from a sample of 2121 matched ChaMP/SDSS sources. Their cuts retain 92% of the spectroscopically confirmed stars in the original sample while excluding 99.6% of the 684 spectroscopically confirmed extragalactic sources. Fewer than 3% of the sources in their final catalog are previously identified stellar X-ray emitters. For 42 catalog members, spectroscopic classifications are available in the literature. New spectral classifications and H-alpha measurements are presented for an additional 79 stars. The catalog is dominated by main-sequence stars; the authors estimate the fraction of giants in ChESS to be ~10%. They identify seven giant stars (including a possible Cepheid and an RR Lyrae star) as ChaMP sources, as well as three cataclysmic variables. They derive distances from ~10 to 2000 pc for the stars in the catalog using photometric parallax relations appropriate for dwarfs on the main sequence and calculate their X-ray and bolometric luminosities. These stars lie in a unique space in the L<sub>X</sub>-distance plane, filling the gap between the nearby stars identified as counterparts to sources in the ROSAT All Sky Survey and the more distant stars detected in deep Chandra and XMM-Newton surveys. For 36 newly identified X-ray-emitting M stars, the authors calculated L<sub>H-alpha</sub>/L<sub>bol</sub>. The quantities L<sub>H-alpha</sub>/L<sub>bol</sub> and L<sub>X</sub>/L<sub>bol</sub> are linearly related below L<sub>X</sub>/L<sub>bol</sub> ~ 3 x 10<sup>-4</sup>, while L<sub>H-alpha</sub>/L<sub>bol</sub> appears to turn over at larger L<sub>X</sub>/L<sub>bol</sub> values. Stars with reliable SDSS photometry have an ~0.1 mag blue excess in u-g, likely due to increased chromospheric continuum emission. Photometric metallicity estimates suggest that the sample is evenly split between the young and old disk populations of the Galaxy; the lowest activity sources belong to the old disk population, a clear signature of the decay of magnetic activity with age. This table was created by the HEASARC in January 2009 based on the electronic version of Tables 2 and 3 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/champlanex
- Title:
- ChaMPlane Galactic Bulge and Center X-Ray Source Catalog
- Short Name:
- CHAMPLANEX
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- This table contains the Chandra Multiwavelength Plane (ChaMPlane) Survey catalog of X-ray point sources in the window and four Galactic bulge fields, specifically all source detections with net counts >= 1 in the 0.3-8 keV broad band. In the reference paper, the authors present the log N-log S and spatial distributions of X-ray point sources in seven Galactic bulge (GB) fields within 4 degrees of the Galactic center (GC). They compare the properties of 1159 X-ray point sources discovered in their deep (100 ks) Chandra observations of three low extinction Window fields near the GC with the X-ray sources in the other GB fields centered around Sgr B2, Sgr C, the Arches Cluster, and Sgr A* using Chandra archival data. To reduce the systematic errors induced by the uncertain X-ray spectra of the sources coupled with field-and-distance-dependent extinction, they classify the X-ray sources using quantile analysis and estimate their fluxes accordingly. The result indicates that the GB X-ray population is highly concentrated at the center, more heavily than the stellar distribution models. It extends out to more than 1.4 degrees from the GC, and the projected density follows an empirical radial relation inversely proportional to the offset from the GC. They also compare the total X-ray and infrared surface brightness using the Chandra and Spitzer observations of the regions. The radial distribution of the total infrared surface brightness from the 3.6-micron band images appears to resemble the radial distribution of the X-ray point sources better than that predicted by the stellar distribution models. Assuming a simple power-law model for the X-ray spectra, the closer to the GC, the intrinsically harder the X-ray spectra appear, but adding an iron emission line at 6.7 keV in the model allows the spectra of the GB X-ray sources to be largely consistent across the region. This implies that the majority of these GB X-ray sources can be of the same or similar type. Their X-ray luminosity and spectral properties support the idea that the most likely candidate is magnetic cataclysmic variables (CVs), primarily intermediate polars (IPs). Their observed number density is also consistent with the majority being IPs, provided the relative CV to star density in the GB is not smaller than the value in the local solar neighborhood. This table was created by the HEASARC in January 2010, based on the electronic version of Table 2 from the reference paper, which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
- ID:
- ivo://nasa.heasarc/champsdssa
- Title:
- CHAMP/SDSS Nearby Low-Luminosity AGN Catalog
- Short Name:
- CHAMPSDSSA
- Date:
- 07 Mar 2025
- Publisher:
- NASA/GSFC HEASARC
- Description:
- The combination of the Sloan Digital Sky Survey (SDSS) and the Chandra Multiwavelength Project (ChaMP; Green et al. 2004, ApJS, 150, 43) currently offers the largest and most homogeneously selected sample of nearby galaxies for investigating the relations between X-ray nuclear emission, nebular line emission, black hole masses, and the properties of the associated stellar populations. The authors provide X-ray spectral fits and valid uncertainties for all the galaxies with counts ranging from 2 to 1325 (mean 76, median 19). They present in their paper novel constraints that both X-ray luminosity L<sub>X</sub> and X-ray spectral energy distribution bring to the galaxy evolutionary sequence HII -> Seyfert/Transition Object -> LINER -> Passive suggested by optical data. In particular, the authors show that both L<sub>X</sub> and Gamma, the slope of the power law that best fits the 0.5 - 8 keV spectra, are consistent with a clear decline in the accretion power along the sequence, corresponding to a softening of their spectra. This implies that, at z ~ 0, or at low-luminosity active galactic nucleus (AGN) levels, there is an anticorrelation between Gamma and L/L<sub>Edd</sub>, opposite to the trend which is exhibited by high-z AGN (quasars). The turning point in the Gamma - L/L<sub>Edd</sub> LLAGN + quasars relation occurs near Gamma ~ 1.5 and L/L<sub>Edd</sub> ~ 0.01. Interestingly, this is identical to what stellar mass X-ray binaries exhibit, indicating that the authors have probably found the first empirical evidence for an intrinsic switch in the accretion mode, from advection-dominated flows to standard (disk/corona) accretion modes in supermassive black hole accretors, similar to what has been seen and proposed to happen in stellar mass black hole systems. The anticorrelation the authors find between Gamma and L/L<sub>Edd</sub> may instead indicate that stronger accretion correlates with greater absorption. Therefore, the trend for softer spectra toward more luminous, high-redshift, and strongly accreting (L/L<sub>Edd</sub> >~ 0.01) AGNs/quasars could simply be the result of strong selection biases reflected in the dearth of type 2 quasar detections. The cross-match of all ChaMP sky regions imaged by Chandra/ACIS with the SDSS DR4 spectroscopic footprint results in a parent sample of 15,955 galaxies on or near a chip and a subset of 199 sources that are X-ray detected. Among those, only 107 sources have an off-axis angle (OAA) Theta <0.2 degrees and avoid ccd=8 due to high serial readout noise; these 107 objects comprise the main sample that the authors employ for this study and that are listed in this table. The authors performed direct spectral fits to the X-ray counts distribution using the full instrument calibration, known redshift, and Galactic 21-cm column nH<sub>Gal</sub>. Source spectra were extracted from circular regions with radii corresponding to energy encircled fractions of ~90%, while the background region encompasses a 20 arcsec annulus, centered on the source, with separation 4 arcsecs, from the source region. Any nearby sources were excised, from both the source and the background regions. The spectral fitting was done via yaxx ('Yet Another X-ray eXtractor': Aldcroft 2006, BAAS, 38, 376), an automated script that employs the CIAO Sherpa tool. Each spectrum was fitted in the range 0.5 - 8 keV by two different models: (1) a single power law plus absorption fixed at the Galactic 21-cm value (model 'PL'), and (2) a fixed power law of photon index Gamma = 1.9 plus intrinsic absorption of column nH (model 'PLfix'). For the nine objects with more than 200 counts, the authors employed a third model in which both the slope of the power law and the intrinsic absorption were free to vary (model 'PL_abs'). This table was created by the HEASARC in January 2012 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/705/1336/">CDS Catalog J/ApJ/705/1336/</a> file table1.dat. This is a service provided by NASA HEASARC .
