BeppoSAX High-Energy Large Area Survey (HELLAS) Radio Source Catalog

The 20 HELLAS sources with Declinations south of -40<sup>o</sup> were observed with the ATCA, while the 127 sources with more northerly Declinations were observed with the VLA. For these latter sources a complete covering at 20 cm down to the 5-sigma flux limit of 2.5 mJy is already available with the NRAO/VLA Sky Survey (NVSS) while the FIRST survey (Faint Images of the Radio Sky at Twenty centimeters) is available only for 27 HELLAS sources (5-sigma limit of ~ 1 mJy).In order to obtain information also on the radio spectral properties of the HELLAS sources the authors adopted the following strategy.

All the 147 HELLAS sources were observed at 6 cm down to a 1 -sigma flux limit of ~ 0.10 - 0.25 mJy. For the 20 HELLAS sources observed with the ATCA, they took advantage of the fact that the 6 and 3 cm receivers of the ATCA share a common feed-horn and they observed simultaneously also at 3 cm, obtaining a 3-cm flux limit of ~ 0.22 mJy (1-sigma level). Starting from the radio position of the 53 X-ray/radio associations, the authors searched for optical counterparts within 5 arcseconds from the radio position using the optical positions of the 61 HELLAS sources identified by La Franca et al. (2002, ApJ, 570, 100 = LF02), the USNO-A2.0 1 optical catalog, the APM 2 optical catalog and the NASA Extragalactic Database (NED). 24 X-ray/radio associations have been identified with sources in LF02 (10 Type 1 AGN, 4 Type 2 AGN, 2 BL Lacs, 3 Clusters, 4 ELGs and 1 Radio galaxy), 1 has been identified with a z = 0.708 Radio galaxy in the Lockman Hole using NED (see Table 2 source 116 in Lehmann et al. 2000, A&A, 354, 35 for a description of this source), 13 have an optical (R-band) identification in the USNO and/or APM catalogue while 15 X-ray/radio associations do not have an optical identification brighter than R=20.

This table was created by the HEASARC in July 2014 based on <a href="cdsarc.cds.unistra.fr/ftp/cats/J/MNRAS/342/575">CDS Catalog J/MNRAS/342/575</a> file table1.dat. There was a minor update to the HEASARC's implementation in June 2022 to make the two probability parameters into unitless quantities for improved clarity. This is a service provided by NASA HEASARC .