Spectrographic observations of the ionized iron coronal emission lines at Pic du Midi Observatory (F) in the mid-60s

This paper is dedicated to the memory of Jean Rösch, a great figure in astronomy in the years 1947–1981 who designed, among several innovative devices, a 15-cm spectro-coronagraph. This instrument was installed at Pic du Midi observatory (south-west France), was in use during the mid-60s, fully dedicated to the observation from the ground of the coronal highly ionized iron lines, which was a true challenge at that time. This program is here reconsidered in the context of the time, at Pic du Midi observatory, which has been the cradle of routine visual coronal observations initiated by Bernard Lyot. We take advantage of this review to underline that the goals and objectives of this ground-based coronal program are taken over since 2008, by an Indian team from Bangalore (Indian Institute of Astrophysics), through a space mission (ADITYA-L1 or Sun in Sanskrit), showing a-posteriori the very innovative aspects developed with the help of this 15-cm spectro-coronagraph and thanks to the skills of J. Rösch’s collaborators.