Photografic archive of solar images
Full disc photospheric and Hα photographs were taken from 1957 until 1991. Calcium II K full disc images were also taken from 1958 to 1980 with a spectroheliograph Töpfer and a refractor (f= 220 cm). The images have been stored in 2020 at the ETH Zurich University Archives.
- Calcium II K (list in preparation)