It is a pleasure to thank the ESO infrared support group at La Silla for their dedicated help and the staff at UKIRT for their assistance. We are particularly indebted to Tom Geballe and John Davies for their spectroscopic service observations. We have benefitted from very fruitful discussions with Steve Shore and Rolf Walder and thank Thomas Dumm for his assistance in relation to the Fabry-Pérot transmission. HS acknowledges the financial support of the Swiss National Foundation. The UK Particle Physics and Astronomy Research Council are thanked for financial support to SM and JT.
© European Southern Observatory (ESO) 1997
Online publication: July 8, 1998