1995A&A...300..453B

A non-LTE line formation calculation for nickel in the ionisation stages IV through VI is introduced. The data for radiative bound-bound transitions which have been derived as part of this work are described and their accuracy is evaluated. The theoretical non-LTE spectrum of Ni IV, V, VI is compared to observations of BD+75 325 and Feige 67 both of which are classified as sdO stars. Together with the non-LTE spectrum of iron in the ionisation stages IV through VI this work provides a powerful tool for abundance analyses of iron group elements in objects such as sdO stars.