BeppoSAX/PDS identification of the true counterpart of the Piccinotti source H0917-074

Abstract

High energy emission has been discovered serendipitously by the BeppoSAX/PDS telescope in the ~1.3 degree field of view around the Piccinotti source H0917-074. A re-pointing of BeppoSAX/NFI has allowed the association of this emission with the Seyfert 2 galaxy MCG-1-24-12 which lies within the original HEAO1/A2 error box of H0917-074. This is the first PDS serendipitous discovery of a Seyfert 2 galaxy and the first detection of MCG-1-24-12 in the X-ray domain. The measured 2-10 keV flux of MCG-1-24-12 is ~1 x 10^(-11) erg cm^(-2) s^(-1) compatible with the Piccinotti HEAO-1/A2 observation. This is a factor of ~6 greater than that observed from EXO0917.3-0722, originally suggested as the counterpart of the Piccinotti source. The 2-10 keV spectrum of MCG-1-24-12 shows the presence of Fe K_alpha emission together with an absorption feature at ~8.7 keV. At high energies, the Seyfert 2 still dominates and the observed 20-100 keV flux is ~4 x 10^(-11)erg cm^(-2) s^(-1).