This database contains the 70 `discrete' (i.e., more compact than a few arc minutes) Einstein IPC X-ray sources in the direction of the Small Magellanic Cloud (SMC) that are tabulated in Table 2A of Wang & Wu (1992, ApJS, 78, 391). For full details about the data processing and selection criteria used to create the original source catalog, the above reference should be consulted. This is a service provided by NASA HEASARC .

This table contains some of the results from an in-depth study of low-mass X-ray binaries (LMXBs) detected in the nearby lenticular galaxy NGC 3115 using the Megasecond Chandra X-ray Visionary Project observation (total exposure time 1.1 Ms). In total the authors found 136 candidate LMXBs in the field and 49 in globular clusters (GCs) above 2-sigma detection, with 0.3-8 keV luminosity L_X ~ 10³⁶ - 10³⁹ erg s^-1. Other than 13 transient candidates, the sources overall have less long-term variability at higher luminosity, at least at L_X >~ 2 x 10³⁷ erg s^-1. In order to identify the nature and spectral state of these sources, the authors compared their collective spectral properties based on single-component models (a simple power law or a multicolor disk) with the spectral evolution seen in representative Galactic LMXBs. The authors found that in the L_X vs. photon index Gamma_PL and L_X versus disk temperature kT_MCD plots, most of their sources fall on a narrow track in which the spectral shape hardens with increasing luminosity below L_X ~ 7 x 10³⁷ erg s^-1, but is relatively constant (Gamma_PL ~ 1.5 or kT_MCD ~ 1.5 keV) above this luminosity, which is similar to the spectral evolution of Galactic neutron star (NS) LMXBs in the soft state in the Chandra bandpass. Therefore, the authors identified the track as the NS LMXB soft-state track and suggested sources with L_X <~ 10³⁷ erg s^-1 as atolls in the soft state and those with L_X >~ 10³⁷ erg s^-1 as Z sources. Ten other sources (five are transients) displayed significantly softer spectra and are probably black hole X-ray binaries in the thermal state. One of them (a persistent source) is in a metal-poor GC. The 11 Chandra observations of NGC 3115 are listed in Table 1 of the reference paper. They were made during three epochs: one in 2001,two in 2010, and nine in 2012. All observations used the imaging array of the AXAF CCD Imaging Spectrometer (ACIS). This table contains the properties of the 482 detected point sources in the merged and single Chandra ACIS observations of NGC 3115 above a 2-sigma threshold and after eliminating a number of spurious sources associated with bright streaks on the ACIS-S1 chip and (in one case) on a CCD edge. 469 of these sources (indicated by values of obs_flag = '0') have a single entry in this table, based on their properties as derived from all of the available Chandra data for that position. There are 13 transient sources (having obs_flag = 'h') for which an additional entry is provided referring to their properties in the "high state", and based on the combination of their high-state observations, as shown in Figures 3(a) - 3(d) in the reference paper. For source number 198, there is a second additional entry provided referring to its properties in the "low state", and based on the combination of its low-state observations, as shown in Figure 3(c) in the reference paper. Thus, there are 496 entries (rows) in this table, i.e., 482 + 13 + 1. This table was created by the HEASARC in August 2015 based on the union of the machine-readable versions of Table 3 (the master source catalog) and Table 4 (the source counts, fluxes and hardness ratios in the merged observations) that were obtained from the ApJ web site. It does not contain the source counts and fluxes in the individual observations which were given in Table 5 of the reference paper. This is a service provided by NASA HEASARC .

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 L_X 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 L_X > 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 .

A very sensitive X-ray investigation of the giant H II region N11 in the Large Magellanic Cloud (LMC) was performed using the Chandra X-ray Observatory in which 165 point sources were detected. The 300-ks observation reveals X-ray sources with luminosities (if at the 50 kpc distance of the LMC) down to 10³² erg s^-1, increasing the number of known point sources in the field by more than a factor of five. Among these detections are 13 massive stars (3 compact groups of massive stars, 9 O stars, and one early B star) with log(L_X/L_BOL) ~ -6.5 to -7, which may suggest that they are highly magnetic or colliding-wind systems. On the other hand, the stacked signal for regions corresponding to undetected O stars yields log(L_X/L_BOL) ~ -7.3, i.e., an emission level comparable to similar Galactic stars despite the lower metallicity. Other point sources coincide with 11 foreground stars, 6 late-B/A stars in N11, and many background objects. This observation also uncovers the extent and detailed spatial properties of the soft, diffuse emission regions, but the presence of some hotter plasma in their spectra suggests contamination by the unresolved stellar population. The Chandra ACIS-I observations of N11 were made in six separate segments within two months in 2007. As summarized in Table 1, the exposure time of each segment was 42-49 ks and the roll angle ranged from 130 to 188 degrees Cleaning of significant background flares, together with a correction for the dead time of the six observations, resulted in a total of 280 ks useful exposure for the subsequent analysis. A combination of source detection algorithms (wavelet, sliding-box, and maximum likelihood centroid fitting) were applied to unsmoothed data in three bands: soft (S): 0.5-2.0 keV, hard (H): 2-8 keV, and total (T): 0.5-8 keV. The final source list contains 165 sources with local false detection probability P < 10^-6 in at least one band (Poisson statistics were used in calculating the significance of a source detection above the local count background). The source detection, though optimized for point-like sources, includes a few strong peaks of diffuse X-ray emission, chiefly associated with the SNR N11L, which lies about ~7' west of the field center. The authors calculated the net (background-subtracted) count rates in four sub-bands (S1 = 0.5-1.0 keV, S2 = 1-2 keV, H1 = 2-4 keV and H2 = 4-8 keV, which were later added to form the count rates in the broader bands (S, H, and T). Source counts for each sub-band were then extracted within the 70% energy-encircled radius (EER) of the PSF, whose size depends on the off-axis angle of the source in the exposure and of the energy band under consideration. A background correction was also applied. Finally, count rates were derived by dividing source net counts by their effective exposure times (values at the source positions in the exposure map of the energy band under consideration), leading to equivalent on-axis values. It should be noted that the presented count rates have thus been corrected for the full PSF and for the effective exposure, which accounts not only for the telescope vignetting, but also for the degradation of the detector sensitivity over time. Therefore, the actual number of counts in a detection aperture is not simply a count rate multiplied by an exposure of 280 ks. The difference could be up to a factor of ~2, depending on a source's spectral shape. The authors searched for counterparts to their X-ray sources in several catalogs: the USNO-B1.0 Catalog (Monet et al. 2003), the Guide Star Catalog V2.3.2 (GSC, Lasker et al. 2008), the 2MASS All-Sky Catalog of Point Sources (Cutri et al. 2003), the Magellanic Clouds Photometric Survey (MCPS; Zaritsky et al. 2004, AJ, 128, 1606), the IRSF Magellanic Clouds Point Source Catalog (Kato et al. 2007, PASJ, 59, 615)), the DENIS Catalogue toward Magellanic Clouds (DCMC; Cioni et al. 2000, A&AS,

This table contains the results of a pair of 100 ks Chandra observations of the Small Magellanic Cloud (SMC) to survey high-mass X-ray binaries (HMXBs), stars, and low-mass X-ray binaries (LMXBs)/cataclysmic variables down to L_X = 4.3 x 10³² erg s^-1. The two SMC Deep Fields (DFs) are located in the most active star-forming region of the SMC bar, with Deep Field-1 positioned at the most pulsar-rich location identified from previous surveys. Two new pulsars were discovered in outburst, CXOU J004929.7-731058 (P = 892 s) and CXOU J005252.2-721715 (P = 326 s), and three new HMXB candidates were identified. Of the 15 Be-pulsars now known in the field, 13 were detected, with pulsations seen in 9 of them. Ephemerides demonstrate that 6 of the 10 pulsars known to exhibit regular outbursts were seen outside their periastron phase, and quiescent X-ray emission at L_X = 10^(33-34) erg s^-1 is shown to be common. Comparison with ROSAT, ASCA, and XMM-Newton catalogs resulted in positive identification of several previously ambiguous sources. Bright optical counterparts exist for 40 of the X-ray sources, of which 33 are consistent with early-type stars (M_V < -2, B-V < 0.2), and are the subject of a companion paper to the reference paper. The results point to an underlying HMXB population density up to double that of active systems. The full catalog of 394 point sources is presented in this table; detailed analyses of the source timing and spectral properties are available in the reference paper. The aim-points for these Chandra observations were as follows: DF1 had J2000.0 coordinates of 00 53 34.50 -72 26 43.2 and DF2 had J2000.0 coordinates of 00 50 41.40 -73 16 10.3. This table was created by the HEASARC in August 2010 based on the electronic version of Table 2 from the reference paper which was obtained from the ApJ web site. This is a service provided by NASA HEASARC .

This table contains the results of a study of the X-ray point-source population of the 30 Doradus (30 Dor) star-forming complex in the Large Magellanic Cloud (LMC) using high spatial-resolution X-ray images and spatially-resolved spectra obtained with the Advanced CCD Imaging Spectrometer (ACIS) on board the Chandra X-Ray Observatory. The observation of ~21 ks was made on 1999 September 21 and placed the cluster R136 at the aim point of the ACIS Imaging Array (ACIS-I). This table lists the the X-ray sources detected in the 17' x 17' field centered on R136, the massive star cluster which lies at the center of the main 30 Dor nebula. 20 of the 32 Wolf-Rayet stars in the ACIS field are detected. The cluster R136 is resolved at the sub-arcsecond level into almost 100 X-ray sources, including many typical O3-O5 stars, as well as a few bright X-ray sources which had been previously reported. Over 2 orders of magnitude of scatter in the X-ray luminosity L_x (calculated assuming a distance of 50 kpc) is seen among R136 O stars, suggesting that X-ray emission in the most massive stars depends critically on the details of wind properties and the binarity of each system, rather than reflecting the widely reported characteristic value L_x/L_bol ~ 10^-7. Such a canonical ratio may exist for single massive stars in R136, but these data are too shallow to confirm this relationship. Through this and more recent X-ray studies of 30 Dor, the complete life cycle of a massive stellar cluster can be revealed. This HEASARC table contains both the primary high-significance X-ray sources as well as some lower-significance tentative X-ray sources. The latter sources should not be considered definitive. A subsequent Chandra observation of this field, with several times the exposure of this observation, will result in a longer, more complete list of point sources than that given in this paper. This table was created by the HEASARC in February 2007 based on the merger of electronic versions of Tables 1, 2 and 5 from the above reference which were obtained from the AJ website. It does not include the results from the spectral analysis of 49 of the X-ray sources having a photometric significance (signal-to-noise ratio) greater than 2 which are presented in Tables 3 and 4 of the reference paper. This is a service provided by NASA HEASARC .

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 f_X = 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 .

The authors observed the nearby, low-density globular cluster M71 (NGC 6838) with the Chandra X-Ray Observatory to study its faint X-ray populations. Five X-ray sources were found inside the cluster core radius, including the known eclipsing binary millisecond pulsar (MSP) PSR J1953+1846A. The X-ray light curve of the source coincident with this MSP shows marginal evidence for periodicity at the binary period of 4.2hr. Its hard X-ray spectrum and luminosity resemble those of other eclipsing binary MSPs in 47 Tuc, suggesting a similar shock origin of the X-ray emission. A further 24 X-ray sources were found within the half-mass radius r_h, reaching to a limiting luminosity of 1.5 x 10³⁰ ergs/s (0.3-8 keV). From a radial distribution analysis, the authors find that 18 +/- 6 of these 29 sources are associated with M71, somewhat more than predicted, and that 11 +/- 6 are background sources, both Galactic and extragalactic. M71 appears to have more X-ray sources in the range L_X = 10³⁰ - 10³¹ ergs/s than expected by extrapolating from other studied clusters using either mass or collision frequency. In their paper, the authors explore the spectra and variability of these sources and describe the results of ground-based optical counterpart searches. The authors obtained a 52.4 ks Chandra observation (ObsID 5434) of M71 (nominal center of cluster at J2000.0 RA and Dec of 19 53 46.1 +18 46 42) on 2004 December 20-21 using the Advanced CCD Imaging Spectrometer (ACIS) in very faint (VF), timed-exposure mode with a 3.141s frame time. They searched for X-ray sources in the observed field by employing techniques described in Tennant (2006, AJ, 132, 1372) which use a circular Gaussian approximation to the point-spread function (PSF). Within twice the M71 half-mass radius (r_h = 1.65 arcminutes), they set the signal-to-noise threshold (S/N) for detection to 2.0, but also required the number of source counts to be at least 5 times the statistical uncertainty in the local background estimate. The empirical relation derived by Tennant, C_min = (S/N)²/0.81, then implies a point-source sensitivity limit of about 4.9 counts for r_M71 <= 2r_h and in the energy band 0.3-8.0 keV. Because of the increase in PSF size with off-axis distance and the associated increase in background within a detection cell, for R_M71 > 2r_h they set the S/N threshold for detection to 2.4 and again required the number of source counts to be at least 5 times the statistical uncertainty in the local background estimate. The point-source sensitivity limit thus rises to about seven counts. This table contains 63 X-ray sources and their optical/infrared counterpart information, if any, for those sources with r_M71 <= 2r_h which are listed in Table 1 of the reference paper: these sources have name prefixes of s01 to s63. It also contains 73 X-ray sources and their optical/infrared counterpart information, if any, for those sources with r_M71 > 2r_h which are listed in Table 2 of the reference paper: these sources have name prefixes of ss01 to ss59 and is01 to is14. Each entry in this table corresponds to an X-ray source if there is no counterpart information or only a single identified counterpart or to a particular X-ray source and counterpart match if there are multiple counterpart identifications. There are thus 165 entries in this HEASARC table corresponding to 136 X-ray sources. This table was created by the HEASARC in March 2011 based on the electronic version of Tables 1 and 2 of the reference paper which were obtained from the CDS (their catalog J/ApJ/687/1019 files table1.dat and table2.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 .