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Chandra Bulge Field X-Ray Point Source Catalog
Apparently diffuse X-ray emission has been known to exist along the central quarter of the Galactic Plane since the beginning of X-ray astronomy; this is referred to as the Galactic Ridge X-ray emission (GRXE). Recent deep X-ray observations have shown that numerous X-ray point sources account for a large fraction of the GRXE in the hard band (2 - 8 keV). However, the nature of these sources is poorly understood. Using the deepest X-ray observations made in the Chandra bulge field, the authors present the result of a coherent photometric and spectroscopic analysis of individual X-ray point sources for the purpose of constraining their nature and deriving their fractional contributions to the hard-band continuum and Fe K line emission of the GRXE. Based on the X-ray color-color diagram, they divided the point sources into three groups: A (hard), B (soft and broad spectrum), and C (soft and peaked spectrum). The group A sources are further decomposed spectrally into thermal and non-thermal sources with different fractions in different flux ranges. From their X-ray properties, the authors speculate that the group A non-thermal sources are mostly active galactic nuclei and the thermal sources are mostly white dwarf (WD) binaries such as magnetic and non-magnetic cataclysmic variables (CVs), pre-CVs, and symbiotic stars, whereas the group B and C sources are X-ray active stars in flares and quiescence, respectively. In the log N - log S curve of the 2 - 8 keV band, the group A non-thermal sources are dominant above ~10<sup>-14</sup> erg/cm<sup>2</sup>/s, which is gradually taken over by Galactic sources in the fainter flux ranges. The Fe K-alpha emission is mostly from the group A thermal (WD binaries) and the group B (X-ray active stars) sources. The authors retrieved 10 archived data sets of the Chandra bulge field (CBF) taken with the Advanced CCD Imaging Spectrometer-I (ACIS-I; 0.5 - 8.0 keV energy band with a spectral resolution of ~280 eV for the full width at half-maximum at 5.9keV) array on board Chandra. The observations were carried out from 2008 May to August with a total exposure time of ~900 ks. The authors first extracted point-source candidates using the wavdetect algorithm in the CIAO package. They set the significance threshold at 2.5 x 10<sup>-5</sup>, implying that one false positive detection would be expected at every 4 x 10<sup>4</sup> trials. As a result, 2596 source candidates were found. The number of their source candidates is nearly the same as that found by Revnivtsev et al.(2009, A&A, 507, 1211) in the same region. To select significant point sources from the candidates, the authors examined their validity based on their photometric significance (PS) and the probability of no source (P<sub>B</sub>). The PS is defined as the background-subtracted source counts (C<sub>net</sub>) divided by its background counts normalized by the area. P<sub>B</sub> is the probability that the source is attributable to a background fluctuation, assuming Poisson statistics. The authors recognized a source to be valid if it satisfied both these criteria: PS >= 1.0 and P<sub>B</sub> <= 1.0 x 10<sup>-2</sup>. As a result, they obtained 2002 valid point sources. This table was created by the HEASARC in December 2014 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJ/766/14">CDS catalog J/ApJ/766/14</a> file table2.dat. This is a service provided by NASA HEASARC .
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ChaMPlane Galactic Bulge and Center X-Ray Source Catalog
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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 .
Galactic Center Chandra X-Ray Point Source Catalog
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This table contains a catalog of 9017 X-ray sources identified in Chandra observations of a 2 degrees by 0.8 degrees field around the Galactic center. This enlarges the number of known X-ray sources in the region by a factor of 2.5. The catalog incorporates all of the ACIS-I observations as of 2007 August, which total 2.25 Ms of exposure. At the distance to the Galactic center (8 kpc), we are sensitive to sources with luminosities of 4 x 1032 erg s-1 (0.5-8.0 keV; 90% confidence) over an area of 1 degree2, and up to an order of magnitude more sensitive in the deepest exposure (1.0 Ms) around Sgr A*. The positions of 60% of the sources are accurate to <1 arcsecond (95% confidence), and 20% have positions accurate to <0.5 arcsec. The authors search for variable sources, and find that 3% exhibit flux variations within an observation, and 10% exhibit variations from observation-to-observation. They also find one source, CXOUGC J174622.7-285218, with a periodic 1745 s signal (1.4% chance probability), which is probably a magnetically accreting cataclysmic variable. The authors compare the spatial distribution of X-ray sources to a model for the stellar distribution, and find 2.8 sigma evidence for excesses in the numbers of X-ray sources in the region of recent star formation encompassed by the Arches, Quintuplet, and Galactic center star clusters. These excess sources are also seen in the luminosity distribution of the X-ray sources, which is flatter near the Arches and Quintuplet than elsewhere in the field. These excess point sources, along with a similar longitudinal asymmetry in the distribution of diffuse iron emission that has been reported by other authors, probably have their origin in the young stars that are prominent at a galactic lonitude ~ 0.1 degrees. This tables was designed to be inclusive, so sources of questionable quality are included, according to the authors. For instance, 134 sources have net numbers of counts in the 0.5-8.0 keV band that are consistent with 0 at the 90% confidence level. These sources are only detected in a single band and are presumably either very hard or very soft, detected in single observations because they were transients, or detected in stacked observations with wvdecomp at marginal significance. The authors have chosen to include them because they passed the test based on Poisson statistics from Weisskopf et al. (2007, ApJ, 657, 1026). The observations which were used to generate the source list herein tabulated are listed in Table 1 of the reference paper. This HEASARC table GALCENCXO supercedes and replaces the previous HEASARC tables CHANGALCEN and CHANC150PC, which were based on Muno et al. (2003, ApJ, 589, 225) and Muno et al. (2006, ApJS, 165, 173), respectively. This table was created by the HEASARC in March 2009 based on the machine-readable versions of Table 2, 3 and 4 from the paper which were obtained from the electronic ApJ website. The information on short-term variability given in Table 5 of the reference paper was not included in this HEASARC table, notice. This is a service provided by NASA HEASARC .
Chandra Point Sources in 18 Distant Galaxy Clusters
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With the superb angular resolution of the Chandra Observatory, it is now possible to detect X-ray point sources, either embedded in galaxy clusters or along the cluster line of sight, which could not be resolved by previous instruments. This now allows studies of source counts in distant cluster fields. The authors want to analyze the inner region of clusters of galaxies to check for the presence of any over-density of X-ray point sources embedded in the gas diffuse emission. These point sources are possible AGN belonging to the clusters and could contaminate the cluster emission. The authors used a sample of 18 distant (0.25 < z < 1.01) galaxy clusters from the Chandra archive to construct the log N - log S relation, in both the soft and hard energy bands, for the X-ray point sources detected in the central cluster region to be compared with the counts of point sources detected in similarly deep fields without clusters. The authors find a ~2-sigma excess of cluster region sources at the bright end of the log N - log S distribution. The radial distribution of the brightest X-ray point sources confirms this excess and indicates that it is confined to the inner 0.5 Mpc of the cluster region. The results suggest the possible existence of X-ray sources belonging to the cluster (most probably AGN, given their 0.5-10 keV luminosity ranging from 1043 to 1044 erg s-1): on average one every three clusters. Unlike previous studies, which have mainly investigated the point-source population in the vicinity of the galaxy clusters, the present study analyzes the content of point sources within the 1 Mpc region covered by the cluster extent. This work confirms the findings of other investigators who analyzed the central 1 Mpc region of more massive clusters and/or groups in a similar redshift range. The X-ray source excess found here is much smaller than the excess of radio galaxies found recently in high-z X-ray selected clusters, possibly due to the better sensitivity of the radio observations. The properties of the clusters and of the Chandra exposures in which they were observed are given in Table 1 of the reference paper, and are reproduced below: 
 Cluster Name z RA (J2000) Dec ObsID ACIS Mode Exp N_H L_sb L_hb h m s d ' " ks [units are below] Abell 2125 0.246 15 41 12 +66 16 01 2207 I VF 79.7 2.77 0.13 0.56 ZW CL 1454.8+2233 0.258 14 57 15 +22 20 33 4192 I VF 91.4 3.22 0.23 0.74 MS 1008.1-1224 0.302 10 10 32 -12 39 23 926 I VF 44.2 6.74 0.44 1.57 ZW CL 0024.0+1652 0.394 00 26 35 +17 09 39 929 S VF 36.7 4.19 0.34 2.22 MS 1621.5+2640 0.426 16 23 36 +26 34 21 546 I F 30.0 3.59 0.81 3.41 RXJ 1701.3+6414 0.453 17 01 24 +64 14 10 547 I VF 49.5 2.59 0.64 2.67 CL 1641+4001 0.464 16 41 53 +40 01 46 3575 I VF 44.0 1.02 0.67 2.62 V 1524.6+0957 0.516 15 24 40 +09 57 48 1664 I VF 49.9 2.92 0.89 3.29 MS 0451.6-0305 0.539 04 54 12 -03 00 53 902 S F 41.5 5.18 0.73 4.12 V 1121+2327 0.562 11 20 57 +23 26 27 1660 I VF 66.9 1.30 0.73 3.00 MS 2053.7-0449 0.583 20 56 21 -04 37 51 1667 I VF 43.5 4.96 1.32 4.91 V 1221+4918 0.700 12 21 26 +49 18 30 1662 I VF 79.4 1.44 1.18 4.62 MS 1137.5+6625 0.782 11 40 22 +66 08 18 536 I VF 117.5 1.18 0.81 4.04 RDCSJ 1317+2911 0.805 13 17 21 +29 11 19 2228 I VF 111.3 1.04 0.85 3.59 RDCSJ 1350+6007 0.805 13 50 48 +60 06 54 2229 I VF 58.3 1.76 1.77 7.26 RXJ 1716.4+6708 0.813 17 16 49 +67 08 26 548 I F 51.5 3.71 2.17 9.45 MS 1054.4-0321 0.830 10 56 59 -03 37 37 512 S F 67.5 3.67 1.07 6.61 WARPJ 1415.1+3612 1.013 14 15 11 +36 12 00 4163 I VF 89.2 1.10 1.93 7.54
where Exp is the Chandra exposure time in ks corresponding to the nominal exposure filtered to exclude time periods of high background, N_H is the Galactic hydrogen column density in the direction of the cluster of galaxies, in units of 1020 cm-2, and L_sb and L_hb are the limiting luminosities in units of 1042 erg s-1 for point sources in the clusters in the 0.5-2.0 keV and 2-10 keV
M 87 Chandra X-Ray Point Source Catalog
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The ACIS instrument on board the Chandra X-Ray Observatory has been used to carry out the first systematic study of low-mass X-ray binaries (LMXBs) in M 87 (NGC 4486), the giant elliptical galaxy near the dynamical center of the Virgo Cluster. These images - with a total exposure time of 154 ks - are the deepest X-ray observations obtained as of 2004 of M 87. The authors identified 174 X-ray point sources, (contained in this Browse table) of which ~ 150 are likely LMXBs. This LMXB catalog was combined with deep F475W and F850LP images taken with ACS on the Hubble Space Telescope (HST) (as part of the ACS Virgo Cluster Survey) to examine the connection between LMXBs and globular clusters in M87. Of the 1688 globular clusters in the authors' catalog, a fraction fX = 3.6% +/- 0.5% contain an LMXB. M 87 (NGC 4486) was observed with the Chandra Advanced CCD Imaging Spectrometer (ACIS) for 121 ks on 2002 July 5-6. In this table, only the S3 chip data are used. The data were processed following the CIAO data reduction threads, including a correction for charge transfer inefficiency (CTI). In addition, the authors used 38 ks of archival ACIS observations of M 87 taken on 2000 July 29. These data were processed in a fashion similar to the 2002 July data, except that no CTI correction was possible because the data were telemetered in graded mode. All reductions were carried out with CIAO, version 2.3, coupled with CALDB, version 2.21. In order to combine the event files into a single image for point-source detection, the authors obtained relative offsets by matching the celestial coordinates of two X-ray point sources. The relative offset was ~ 0.5". The total exposure time of the co-added image, excluding four background flares totaling ~ 2.5 ks, was 154 ks. This table was created by the HEASARC in March 2007 based on the CDS table J/ApJ/613/279, file table1.dat. This is a service provided by NASA HEASARC .
NGC 4278 Chandra X-Ray Point Source Catalog
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This table lists some of the properties of the discrete X-ray sources detected in the authors' monitoring program of the globular cluster (GC)-rich elliptical galaxy, NGC 4278, observed with Chandra ACIS-S in six separate pointings, resulting in a co-added exposure of 458 ks. From this deep observation, 236 sources have been detected within the region overlapped by all observations, 180 of which lie within the D25 ellipse angular diameter of the galaxy. These 236 sources range in X-ray luminosity LX from 3.5 x 1036 erg s-1 (with 3-sigma upper limit <= 1 x 1037 erg s-1) to ~2 x 1040 erg s-1, including the central nuclear source which has been classified as a LINER. From optical data, 39 X-ray sources have been determined to be coincident with a GC, these sources tend to have high X-ray luminosity, with 10 of these sources exhibiting LX > 1 x 1038 erg s-1. From X-ray source photometry, it has been determined that the majority of the 236 point sources that have well-constrained colors have values that are consistent with typical low-mass X-ray binary spectra, with 29 of the sources expected to be background objects from the log N-log S relation. There are 103 sources in this population that exhibit long-term variability, indicating that they are accreting compact objects. Three of these sources have been identified as transient candidates, with a further three possible transients. Spectral variations have also been identified in the majority of the source population, where a diverse range of variability has been identified, indicating that there are many different source classes located within this galaxy. This HEASARC table contains the master source list (Table 3 of the reference paper) and the X-ray properties of the sources in the co-added observations (Table 4 of the reference paper), but not the X-ray properties of the sources in the 6 individual observations (Tables 5-10 of the reference paper). The details of the six individual pointings used in this study, e.g., the Chandra ObsIDs, dates, exposure times and cleaned exposure times, are given in Table 1 of the reference paper, and repeated here: 
 Obs. No.OBSID Date Exposure (s) Cleaned Exposure (s) 1 4741 2005 Feb 3 37462.0 37264.5 2 7077 2006 Mar 16 110303.8 107736.7 3 7078 2006 Jul 25 51433.2 48076.2 4 7079 2006 Oct 24 105071.7 102504.6 5 7081 2007 Feb 20 110724.0 107564.5 6 7080 2007 Apr 20 55824.8 54837.5 Total Co-added 470819.5 457984.0
Notes. The pointing OBSID 7181 was taken before OBSID 7080, so to maintain the time sequence of the exposures these observation numbers have been labeled as above in the reference paper. The details of the energy bands and X-ray colors used in this study are given in Table 2 of the reference paper, and repeated here: 
 Band/Color Energy Range/Definition Broad (B) 0.3-8 keV Soft (S) 0.3-2.5 keV Hard (H) 2.5-8 keV Soft 1 (S1) 0.3-0.9 keV Soft 2 (S2) 0.9-2.5 keV Conventional broad (Bc) 0.5-8 keV Conventional soft (Sc) 0.5-2 keV Conventional hard (Hc) 2-8 keV Hardness ratio HR (Hc-Sc)/(Hc+Sc) X-ray color C21 -log(S2) + log(S1) = log(S1/S2) X-ray color C32 -log(H) + log(S2) = log(S2/H)
This table was created by the HEASARC in April 2009 based on machine-readable versions of Tables 3 and 4 from the reference paper which were obtained from the ApJ web site. This is a service provided by NASA HEASARC .
Chandra Galactic Bulge Survey Full X-Ray Point Source Catalog
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This table contains the Chandra source list for the entire area of the Galactic Bulge Survey (GBS) based on the lists provided in Jonker et al. (2011, ApJ, 194, 18: Paper I) and Jonker et al. (2014, ApJS, 210, 18: Paper II). The previous version of this table, based solely on the data presented in Paper I, contained the Chandra source list based on the first three-quarters of the GBS that had been observed as of the date of writing of that paper. Among the goals of the GBS are constraining the neutron star (NS) equation of state and the black hole (BH) mass distribution via the identification of eclipsing NS and BH low-mass X-ray binaries (LMXBs). The latter goal will, in addition, be obtained by significantly enlarging the number of BH systems for which a BH mass can be derived. Further goals include constraining X-ray binary formation scenarios, in particular the common envelope phase and the occurrence of kicks, via source-type number counts and an investigation of the spatial distribution of X-ray binaries, respectively. The GBS targets two strips of 6 degrees by 1 degrees (12 deg2 in total), one above (1o < b < 2o) and the other below (-2o < b < -1o) the Galactic plane in the direction of the Galactic center at X-ray, optical and near-infrared wavelengths. By avoiding the Galactic plane (-1o < b < 1o) the authors limit the influence of extinction on the X-ray and optical emission but still sample relatively large number densities of sources. The survey is designed such that a large fraction of the X-ray sources can be identified from their optical spectra. The X-ray survey, by design, covers a large area on the sky while the depth is shallow, using 2 ks per Chandra pointing. In this way, the authors maximize the predicted number ratio of (quiescent) LMXBs to cataclysmic variables. The survey is approximately homogeneous in depth to a 0.5-10 keV flux of 7.7 x 10-14 erg cm-2 s-1. As of Paper I, the authors had covered about three-fourths (8.3 deg2) of the projected survey area with Chandra observations providing 1234 unique X-ray sources. In Paper II, the authors find 424 additional X-ray sources in the 63 Chandra observations that they report on there. In the papers, the authors discuss the characteristics and the X-ray variability of the brightest of the sources as well as the radio properties from existing radio surveys. They point out an interesting asymmetry in the number of X-ray sources as a function of their Galactic l and b coordinates which is probably caused by differences in average extinction towards the different parts of the GBS survey area. This table was originally ingested by the HEASARC in June 2011 based on an electronic version of Table 3 from Paper I which was obtained from the ApJS web site. The current version of this table was ingested by the HEASARC in January 2014 based on CDS catalog J/ApJS/210,18 file cxogbs.dat, which appears to be the combination of an Table 3 from Paper I with Table 1 from Paper II. This is a service provided by NASA HEASARC .
ASCA Galactic Plane Survey of Faint X-Ray Sources
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Sugizaki et al. (2001) have published a study of faint X-ray sources that were resolved in the ASCA Galactic Plane Survey and their contribution to the galactic ridge X-ray emission, and the present database contains their list of discrete sources. The X-ray emission from the central region of the Galactic plane, |l|<~45 degrees and |b|<~0.4 degrees, was studied in the 0.7 to 10 keV energy band with a spatial resolution of ~3' with the Advanced Satellite for Cosmology and Astrophysics (ASCA) observatory. The authors developed a new analysis method for the ASCA data to resolve discrete sources from the extended Galactic ridge X-ray emission (GRXE). Using the ASCA Gas Imaging Spectrometers (GISs), they successfully resolved 163 discrete sources with X-ray fluxes down to 10-12.5ergs/cm2/s and determined the intensity variations of the GRXE as a function of the Galactic longitude with a spatial resolution of about 1 degree. This database was created by the HEASARC in December 2001 based on the ADC/CDS Catalog J/ApJS/134/77/table2.dat. This is a service provided by NASA HEASARC .
NGC 4649 Chandra X-Ray Point Source Catalog 2
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This table contains the main X-ray source catalog for the Chandra monitoring observations of the 16.5-Mpc distant elliptical galaxy, NGC 4649. The galaxy has been observed with Chandra ACIS-S3 in six separate pointings, reaching a total exposure of 299 ks. There are 501 X-ray sources detected in the 0.3-8.0 keV band in the merged observation or in one of the six individual observations; 399 sources are located within the D25 ellipse. The observed 0.3-8.0 keV luminosities of these 501 sources range from 9.3 x 1036 erg s-1 to 5.4 x 1039 erg s-1. The 90% detection completeness limit within the D25 ellipse is 5.5 x 1037 erg s-1. Based on the surface density of background active galactic nuclei (AGNs) and the detection completeness, we expect ~ 45 background AGNs among the catalog sources (~ 15 within the D25 ellipse). There are nine sources with luminosities greater than 1039 erg s-1, which are candidates for ultraluminous X-ray sources. The nuclear source of NGC 4649 is a low-luminosity AGN, with an intrinsic 2.0-8.0 keV X-ray luminosity of 1.5 x 1038 erg s-1. The X-ray colors suggest that the majority of the catalog sources are low-mass X-ray binaries (LMXBs). The authors find that 164 of the 501 X-ray sources show long-term variability, indicating that they are accreting compact objects, and discover four transient candidates and another four potential transients. They also identify 173 X-ray sources (141 within the D25 ellipse) that are associated with globular clusters (GCs) based on Hubble Space Telescope and ground-based data; these LMXBs tend to be hosted by red GCs. Although NGC 4649 has a much larger population of X-ray sources than the structurally similar early-type galaxies, NGC 3379 and NGC 4278, the X-ray source properties are comparable in all three systems. This HEASARC table contains the main Chandra source catalog of the basic properties of the 501 X-ray detected sources (Table 3 in the reference paper which includes both sources detected in the merged X-ray image as well as a number only detected in the individual observations), and also the information on source counts, hardness ratios and soft and hard X-ray colors in the merged observation for the same 501 X-ray detected sources (Table 4 in the reference paper). It does not contain the information on source counts, hardness ratios and soft and hard X-ray colors for these same sources in the six individual observations that were contained in Tables 5 - 10 of the reference paper. This table was created by the HEASARC in March 2013 based on the electronic version of Tables 3 and 4 from the reference paper which were obtained from the ApJS website.. This is a service provided by NASA HEASARC .
Galactic Center Chandra X-Ray Source Near-IR Counterparts
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This table contains a catalog of 5184 candidate infrared counterparts to X-ray sources detected toward the Galactic center. The X-ray sample contains 9017 point sources detected in this region by the Chandra X-ray Observatory during the past decade, including data from a recent deep survey of the central 2 degrees x 0.8 degrees of the Galactic plane. A total of 6760 of these sources have hard X-ray colors, and the majority of them lie near the Galactic center, while most of the remaining 2257 soft X-ray sources lie in the foreground. The authors have cross-correlated the X-ray source positions with the 2MASS and SIRIUS near-infrared catalogs, which collectively contain stars with a 10-sigma limiting flux of Ks <= 15.6 mag. In order to distinguish absorbed infrared sources near the Galactic center from those in the foreground, they defined red and blue sources as those which have H - Ks >= 0.9 and < 0.9 mag, respectively. The authors find that 5.8% =/- 1.5% (2 sigma) of the hard X-ray sources have real infrared counterparts, of which 228 +/- 99 are red and 166 +/- 27 are blue. The red counterparts are probably comprised of Wolf-Rayet and O stars, high-mass X-ray binaries, and symbiotic binaries located near the Galactic center. Foreground X-ray binaries suffering intrinsic X-ray absorption could be included in the sample of blue infrared counterparts to hard X-ray sources. The authors also find that 39.4% +/- 1.0% of the soft X-ray sources have blue infrared counterparts; most of these are probably coronally active dwarfs in the foreground. There is a noteworthy collection of ~20 red counterparts to hard X-ray sources near the Sagittarius B H II region, which are probably massive binaries that have formed within the last several Myr. For each of the infrared matches to X-ray sources in their catalog, the authors derived the probability that the association is real, based on the source properties and the results of the cross-correlation analysis. These data are included in this catalog and will serve spectroscopic surveys to identify infrared counterparts to X-ray sources near the Galactic center. This table was created by the HEASARC in October 2009 based on the electronic version of Table 3 from the reference paper which was obtained from the Astrophysical Journal web site. This is a service provided by NASA HEASARC .
NGC 2808 Chandra X-Ray Point Source Catalog
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This table contains the sources detected in a Chandra X-ray observation of the Galactic globular cluster NGC 2808, as well as the corresponding XMM-Newton data for those sources which have XMM-Newton X-ray counterparts. Using new Chandra X-ray observations and existing XMM-Newton X-ray and Hubble Space Telescope far-ultraviolet observations, the authors aim to detect and identify the faint X-ray sources belonging to NGC 2808 in order to understand their role in the evolution of globular clusters. The authors classify the X-ray sources associated with the cluster by analysing their colors and variability. Previous observations with XMM-Newton and far-ultraviolet observations with Hubble are re-investigated to help identify the Chandra sources associated with the cluster. The authors compare their results to population synthesis models and observations of other Galactic globular clusters. NGC 2808 was observed with the Chandra X-ray Observatory Advanced CCD Imaging Spectrometer-Imager (ACIS-I) on 2007 June 19-21 (28 months after the XMM-Newton observation referred to the reference paper) for two distinct exposures of 46 and 11 kiloseconds. The authors detect 113 sources, of which 16 fall inside the half-mass radius of NGC 2808 and are concentrated towards the cluster core. This table was created by the HEASARC in February 2009 based on the electronic version of Table 1 from the paper which was obtained from the CDS (their catalog J/A+A/490/641 file table1.dat). This is a service provided by NASA HEASARC .
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