J.M. Smith wishes to thank the United Kingdom Engineering and Physical Sciences Research Council (EPSRC) for financial support and NATO (under Grant CRG 901002) for his visit to Palma, where part of this work was undertaken. R. Oliver acknowledges support from the Spanish Ministry of Science and Education (Grant PB96-0092). J.M. Smith is grateful to J.L. Ballester for kind hospitality during his stay in Palma.
© European Southern Observatory (ESO) 1997
Online publication: April 8, 1998