This research has made use of the SIMBAD database operated at CDS, Strasbourg, France and of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, CALTECH, under contract with the National Aeronautics and Space Administration. To overlay the X-ray data we used an image based on photographic data of the National Geographic Society - Palomar Observatory Sky Survey (NGS-POSS) obtained using the Oschin Telescope on Palomar Mountain. The NGS-POSS was funded by a grant from the National Geographic Society to the California Institute of Technology. The plates were processed into the present compressed digital form with their permission. The Digitized Sky Survey was produced at the Space Telescope Science Institute under US Government grant NAG W-2166. GT acknowledges a Max-Planck Fellowship and the kind hospitality of the ROSAT group during the completion of this project. The ROSAT project is supported by the German Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF/DLR) and the Max-Planck-Gesellschaft (MPG).
© European Southern Observatory (ESO) 1998
Online publication: November 9, 1998