We thank all the people who, at all levels, have made possible the BeppoSAX mission. We also thank all the members of the ASCA team who operate the satellite and maintain the software and database. This work has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, Caltech, under contract with the National Aereonautics and Space Administration, of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the Goddard Space Flight Center and of the Simbad database, operated at CDS, Strasbourg, France. The authors would like to thank the referee, S. Komossa, for her suggestions who improved the quality of the paper. Financial support from Italian Space Agency under the contract ARS-98-119 is ackowledged by C. V., A. C and G.G.C. P. This work was partly supported by the Italian Ministry for University and Research (MURST) under grant Cofin98-02-32. F.N. Aknowledges the NASA grant NAG5-9216.
© European Southern Observatory (ESO) 2000
Online publication: October 30, 19100