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 .

This database contains information on sources detected with the Einstein Observatory Image Proportional Counter (IPC), assembled for the Einstein Observatory Catalog (EOSCAT) of IPC X-ray Sources (2E) and containing over 4000 unique sources (with 6539 separate detections) which were detected with the IPC at a level of significance greater than 3.5 sigma in the broad band (0.2-3.5 keV). This database also contains the list of 277 sources which are known not to have been included in the Einstein Observatory Source Catalog (flagged by supplement = 'Y' in this database). Those which were not detected during the standard Rev1B processing were typically discovered upon visual inspection of the contour diagrams in the Catalog. Others were detected with Rev1B standard processing but left out of the Catalog because of short exposure times or other reasons listed in the "missed_code" field. 258 of these 277 additional sources have no valid signal to noise ratio (SNR) estimate (values of 0.0), while 3 others have SNR values of 3.2 and 3.3, notice. This IPC database is based on NASA Astrophysics Data System (ADS) tables that were created in 1991 and 1993 and were themselves derived from tables provided by Dr. D. E. Harris of the Center for Astrophysics at Harvard-Smithsonian. The HEASARC has a similar catalog in its database called EINSTEIN2E which comprises a more recent version of the IPC source list as archived at the NASA Astronomical Data Center (ADC) and the Center for Astronomical Data at Strasbourg (CDS). EINSTEIN2E has 868 fewer detections than the IPC catalog, notice, for reasons that the HEASARC is unsure of, but that may imply that some of the detections in IPC are not reliable. We have retained the IPC database for reasons of completeness, but caution that detections listed here which have no counterpart in the EINSTEIN2E Catalog should be treated with caution. This IPC database was recreated by the HEASARC in December 2000 to replace a previous version in which we discovered some transcription errors. It is based on NASA Astrophysics Data System (ADS) tables that were created in 1991 and 1993 and were themselves derived from tables provided by Dr. D. E. Harris of the Center for Astrophysics at Harvard-Smithsonian:

 The Einstein IPC Source List From EOSCAT (ADS Creation Date: 26-Dec-1990; ADS Last Revision Date: 04-Nov-1993), D.E. Harris, CfA The EOSCAT List of Missed IPC Sources (ADS Creation Date: 26-Oct-1990; ADS Last Revision Date: 17-Sep-1991), D.E. Harris, CfA 

This is a service provided by NASA HEASARC .

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 .

Soft X-ray (0.2 - 3.5 keV) measurements for all normal, massive, o-type stars surveyed with the Einstein Observatory are presented as a catalog containing 89 detections and 176 upper bounds, together with a detailed discussion of the reduction process. Values of L[x]/L[bol] listed for most stars, range from 10e-5.44 to 10e-7.35; l[x] spans more than 3 orders of magnitude, ranging from 1.5 x 10e31 to 2 x 10e34 ergs se-1. It is noted that at least 30% of o-type stars are variable in X-rays, but that there is little evidence for new objects whose X-ray emission might be significantly enhanced by accretion processes onto a neutron star. For further information, please contact the HEASARC. This is a service provided by NASA HEASARC .

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 .