We thank Norbert Weitzel and Rainer Köhler for providing the data reduction programmes, Rick Hessman for the SED fitting programme and Lynne Hillenbrand, Rainer Lenzen, Michal Simon and Steve Skinner for making available unpublished data. Antonella Natta and the referee Jerome Bouvier provided helpful criticism. We gratefully acknowledge the efficient help by the MAGIC support team for our 2D measurements on Calar Alto, and also the good support given to us by the SHARP and ADONIS and ESO teams during the observations at La Silla. This research has made use of the Simbad database, operated at CDS, Strasbourg (France).
© European Southern Observatory (ESO) 1997
Online publication: July 8, 1998