We wish to thank the ISO spectroscopy data center at the Max-Planck-Institut für Extraterrestrische Physik, in particular D. Kunze, E. Sturm, and D. Lutz for efficient support. S. Unger (Rutherford Appleton Laboratory) helped with the LWS data reduction. We are also grateful to R. Genzel for his encouragement and interest in this project, and D. Downes for comments on the manuscript. The tabulated recombination line coefficients (Storey & Hummer 1995) were obtained from the Centre des Données, Strassbourg. J.M-P. is partially supported by the PNIE of the Spanish CICyT under grant ESP 97-1490-E.
© European Southern Observatory (ESO) 1998
Online publication: April 20, 1998