Dutch Astronomy between 1921 and 1956 David Baneke, VU Amsterdam Symposium honoring Adriaan Blaauw Groningen, 7 April 2014 Leiden Observatory staff (incl. computers and graduate students), 1933 Oosterhoff Kuiper Wesselink Oort Hertzsprung De Sier Woltjer Leiden Observatory, 1920s: - New staff: Pannekoek, Hertzsprung, Woltjer, Oort Willem de SiPer Adriaan Blaauw to DB: Ejnar Hertzsprung “At that Yme, the reputaon of Leiden Observatory was the reputaon of Hertzsprung” Frank Schlesinger to De Sier, 1927: “I have long felt, and I think I have expressed to you, a warm admiraon for the way in which you have made it possible for Hertzsprung to work effecYvely.” Leiden Observatory, 1920s: - New staff: Pannekoek, Hertzsprung, Woltjer, Oort - New graduate program Harlow Shapley to De Sier, 1928: Willem de SiPer “I remember your frequent statement that one principal funcon of your Observatory is to train and export highly capable young astronomers.” Meanwhile … Marcel Minnaert, Amsterdam Utrecht 2 main research tradiYons in Dutch astronomy: Groningen, Leiden: Kapteyn, Hertzsprung, Oort & students, successors Stellar & galacYc astronomy Amsterdam and Utrecht: Pannekoek, Minnaert & students, successors Astrophysics, solar physics Complete astronomy faculty in NL, 1920-1940: Groningen: Minnaert Kapteyn (unYl 1921) Amsterdam: Pannekoek Van Rhijn (from 1921) * Leiden: De Sier (unl 1934) * Hertzsprung * Woltjer Oort (from 1924) * Utrecht: Nijland (unl 1936) Van der Bilt * * * GM RAS P.J. van Rhijn and P. Oosterhoff 1939 Four former Groningen assistants: Bart Bok, Jan Oort, Peter van de Kamp, Jan Schilt 1939 1945: Jan Oort emerges as uncontested leader of Dutch astronomy Post-War plans: - Kenya expedition - ESO - Radio astronomy NAC colloquium on radio astronomy and the 21-cm line, 15 April 1944 Minutes by Adriaan Blaauw, secretary of the NAC Planning ahead: WSRT Jan Oort to Blaauw, 1956: Plenty of opportuniYes; plans for a new giant radio telescope, but NFRA board does not know about it yet. Nancy Roman to Blaauw, 1957: “It sounds like an intriguing mixture of headaches and opportuniYes.” Van Rhijn Minnaert Blaauw Oort De Jager Van de Hulst Nederlandse Astronomen Conferentie, 1941 .