We would like to thank Monique Arnaud for kindly providing the X-ray spectral analysis program, Geoff Bicknell and Neil Killeen for their program to calculate the minimum pressure and Matthew Colless for useful discussions on the optical data. We acknowledge the use of the COSMOS/UKST Southern Sky Catalogue supplied by the Anglo-Australian Observatory. HL acknowledges the support of the Australia-France collaboration fund.
© European Southern Observatory (ESO) 1997
Online publication: June 30, 1998