1. J. Bailey, Anglo-Australian Observatory, Post Office Box 296, Epping, New South Wales 2121, Australia. A. Chrysostomou, J. H. Hough, T. M. Gledhill, A. McCall, S. Clark, Department of Physical Sciences, University of Hertfordshire, College Lane, Hatfield AL10 9AB, UK. F. Ménard, Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, F-38041 Grenoble, CEDEX 9, France. M. Tamura, National Astronomical Observatory, Osawa, Mitaka, Tokyo 181, Japan.