Radiative transition probabilities have been calculated for all forbidden lines connecting the 47 energetically lowest energy levels in singly ionized cobalt using a rather sophisticated atomic structure model. The new HFR data reported in this paper provide an extended and reliable physical basis for astrophysical studies where [Co II] lines play an important role. Some of our calculated A-values have already been included in SN Ia spectral model and have significantly improved the agreement between the synthetic spectra and supernova spectra at early times when cobalt is as abundant as iron in the supernovae (Liu et al. 1997b).
It is a pleasure to thank Dr. W. Liu and Dr. D.J. Jeffery (Oak Ridge National Laboratory) for their interest in this work and for stimulating discussions.