SIMBAD references

The Extended Chandra Deep Field-South (ECDFS) survey consists of four Chandra X-Ray Observatory ACIS-I pointings and covers ~1100 arcmin² (~0.3 deg²) centered on the original CDF-S field to a depth of approximately 228 ks. This is the largest Chandra survey ever conducted at such depth, and only one XMM-Newton survey reaches a lower flux limit in the hard 2.0-8.0 keV band. We detect 651 unique sources: 587 using a conservative source-detection threshold and 64 using a lower source-detection threshold. These are presented as two separate catalogs. Of the 651 total sources, 561 are detected in the full 0.5-8.0 keV band, 529 in the soft 0.5-2.0 keV band, and 335 in the hard 2.0-8.0 keV band. For point sources near the aim point, the limiting fluxes are approximately 1.7x10^–16 and 3.9x10^–16ergs/cm2/s in the 0.5-2.0 and 2.0-8.0 keV bands, respectively. Using simulations, we determine the catalog completeness as a function of flux and assess uncertainties in the derived fluxes due to incomplete spectral information. We present the differential and cumulative flux distributions, which are in good agreement with the number counts from previous deep X-ray surveys and with the predictions from an active galactic nucleus (AGN) population synthesis model that can explain the X-ray background. In general, fainter sources have harder X-ray spectra, consistent with the hypothesis that these sources are mainly obscured AGNs.