Solar Flare Spectroscopy at Pic du Midi Observatory (1956–1968) in the Frame of the International Geophysical Year

In the frame of the International Geophysical Year (IGY 1957-1958), a new program was initiated by Meudon astronomers, under the auspices of Raymond Michard, to study solar flares using high resolution spectral diagnostics. For that purpose, a 4-metre flare spectrograph was first build at Pic du Midi as early as 1956, and a more powerful 9-metre spectrograph was meanwhile designed at Meudon observatory. Then it was transferred to Pic du Midi where it operated successfully until 1968. The laboratory was transformed for another use in 1999. We present in this paper the instrumental developments and summarize the main scientific results.