1. Daniel Georg Lindhagen, Swedish astronomer. Worked at Pulkovo 1847-1855, then at the Stockholm observatory. Photograph by Johannes Jaeger, Stockholm. Original in Gustav Holmberg's collection.
  2. Heinrich Louis d'Arrest, Danish astronomer. Worked on the spectra of red stars. Photograph in the collection Astronomiskt Porträttgalleri, collected by Bernhard Hasselberg, Uppsala University Library, Pictures and Maps Division.
  3. Knut Lundmark, Swedish astronomer, professor at Lund observatory. Worked on the distance of the nebulae and the history of astronomy. By using novae as distance indicators, he argued in 1919 that M31, the Andromeda nebula (as it was then called) in fact was a distant stellar system, much like our own. He was very active in the popularization of astronomy. Photograph taken c. 1937, showing Lundmark at the Lund observatory. Photograph in the collection of Lund observatory.