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Description
The Chandra Deep Field South (CDFS) 1-Megasecond Catalog is the source catalog obtained from a 942 kilosecond exposure, using the Advanced CCD Imaging Spectrometer (ACIS-I) on the Chandra X-ray Observatory. Eleven individual pointings made between 1999 October and 2000 December were combined to generate the final image used for object detection. Catalog generation proceeded simultaneously using two different methods: a method of the authors' own design using a modified version of the SExtractor algorithm, and a wavelet transform technique developed specifically for Chandra observations. The detection threshold was set in order to have less than 10 spurious sources, as assessed by extensive simulations. The catalog as published was subdivided into four sections: the primary list consisting of objects common to the two detection methods, two secondary lists containing sources which were detected by either the SExtractor algorithm alone or by the wavelet technique alone, and the fourth list consisting of possible diffuse or extended sources. The flux limits at the aimpoint for the soft (0.5 - 2 keV) and hard (2 - 10 keV) bands are 5.5 x 10^-17 erg/s/cm^2 and 4.5 x 10^-16 erg/s/cm^2, respectively. The total number of sources is 346; out of them, 307 were detected in the 0.5 - 2 keV band, and 251 in the 2 - 10 keV band. Optical identifications are also presented for the catalogued sources. The primary optical data are R band imaging from VLT/FORS1 to a depth of R ~ 26.5 (Vega). In regions of the field not covered by the VLT/FORS1 deep imaging, the authors use R-band data obtained with the Wide Field Imager (WFI) on the ESO-MPI 2.2 m telescope, as part of the ESO Imaging Survey (EIS), which cover the entire X-ray survey. The FORS1/Chandra offsets are small, ~1 arcsecond. Coordinate cross-correlation finds 85% of the Chandra sources covered by FORS1 R to have counterparts within the 3-sigma error box (>~1.5 arcseconds, depending on off-axis angle and X-ray signal-to-noise). The unidentified fraction of sources, approximately 10% - 15%, is close to the limit expected from the observed X-ray flux to R-band ratio distribution for the identified sample. This online catalog was created by the HEASARC in June 2002 based on machine-readable versions of 2, 3 and 4 of Giacconi et al. (2002) that were obtained from the CDS. This is a service provided by NASA HEASARC .
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