We thank A. Strong for kindly providing the CO and HI maps in electronic form. We thank the night assistants at Observatoire de Haute-Provence for carrying out some of the observations at the 1.2m telescope. The ROSAT project is supported by the Bundesministerium für Bildung, Wissenschaft, Forschung und Technologie (BMBF/DARA) and the Max-Planck-Gesellschaft. C.M. acknowledges support from a CNRS-MPG cooperation contract and thanks Prof. J. Trümper and the ROSAT group for their hospitality and fruitful discussions. This research has made use of the SIMBAD database operated at CDS, Strasbourg, France.
© European Southern Observatory (ESO) 1997
Online publication: July 8, 1998