|
Description
Deep radio observations at 1.4 GHz for the Extended Chandra Deep Field South were performed in 2007 June through September and presented in a first data release (Miller et al. 2008, ApJS, 179, 114). The survey was made using six separate pointings of the Very Large Array with over 40 hr of observation per pointing. In the current study, the authors improve on the data reduction to produce a second data release (DR2) mosaic image. This DR2 image covers an area of about a third of a square degree, reaches a best rms sensitivity of 6 µJy (µJy), and has a typical sensitivity of 7.4 uJy per 2.8" by 1.6" beam. The authors also present a more comprehensive catalog, including sources down to peak flux densities of five or more times the local rms noise, along with information on source sizes and relevant pointing data. In their paper, they discuss in some detail the consideration of whether sources are resolved under the complication of a radio image created as a mosaic of separate pointings, each suffering some degree of bandwidth smearing, and the accurate evaluation of the flux densities of such sources. Finally, the radio morphologies and optical/near-IR counterpart identifications are used to identify 17 likely multiple-component sources so as to arrive at a catalog of 883 radio sources (and also 49 individual components of the 17 multi-component sources), which is roughly double the number of sources contained in the first data release. In order to cover the full E-CDF-S area at near-uniform sensitivity, the authors pointed the VLA at six separate coordinate locations arranged in a hexagonal grid around the adopted center of the CDF-S, viz. RA, Dec (J2000) 03<sup>h</sup> 32<sup>m</sup> 28.00<sup>s</sup>, -27<sup>o</sup> 48' 30.0". The observations were spread over many days on account of the low declination of the field and typically amounted to 5 hr of time per calendar date. The details of the individual pointings are: <pre> Pointing ID R.A. (J2000) DE. (J2000) rms sensitivity for final image ECDFS 1 03:33:22.25 -27:48:30.0 10.5 uJy ECDFS 2 03:32:55.12 -27:38:03.0 9.4 uJy ECDFS 3 03:32:00.88 -27:38:03.0 9.7 uJy ECDFS 4 03:31:33.75 -27:48:30.0 9.5 uJy ECDFS 5 03:32:00.88 -27:58:57.0 10.0 uJy ECDFS 6 03:32:55.12 -27:58:57.0 9.3 uJy </pre> The images corresponding to the six individual pointings were combined to form the final mosaic image (shown in Figure 1 of the reference paper). This HEASARC table contains the catalog of 883 radio sources (Table 3 in the reference paper) and also the catalog of 49 individual components of the 17 multi-component sources (Table 4 in the reference paper), so that there are a total of 932 entries in the present table. To allow users to easily distinguish these types of entry, the HEASARC created a parameter type_flag which is set to 'S' for the 883 source entries and to 'C' for the 49 component entries. The HEASARC created names for the sources following the standard CDS and IAU recommendations for position-based names and using the prefix of '[MBF2013]' for Miller, Bonzini, Fomalont (2013), the first 3 authors and the date of publication of the reference paper. For the components, we have used the names based on the positions of the parent sources and the suffixes 'A', 'B', etc, in order of increasing J2000.0 RA. Thus, for the multi-component source [MBF2013] J033115.0-275518 which has 3 components, there are 4 entries in this table, one for the entire source, and one for each component, e.g.: <pre> Name | type_flag | RA (J2000.0) Dec (J2000.0) [MBF2013] J033115.0-275518 | S | 03 31 15.04 | -27 55 18.8 [MBF2013] J033115.0-275518 A| C | 03 31 13.99 | -27 55 19.9 [MBF2013] J033115.0-275518 B| C | 03 31 15.06 | -27 55 18.9 [MBF2013] J033115.0-275518 C| C | 03 31 17.05 | -27 55 15.2 </pre> The 17 sources thought to consist of multiple components associated with a single host object are each listed with a single aggregate integrated flux density. Gaussian fits to the individual components associated with these sources are separately listed for their components This table was created by the HEASARC in May 2013 based on <a href="https://cdsarc.cds.unistra.fr/ftp/cats/J/ApJS/205/13">CDS Catalog J/ApJS/205/13</a> files table3.dat and table4.dat. This is a service provided by NASA HEASARC .
|
