Published in Private Document 2011/01 in 2011
G. P. Können
There is some confusion about the nationality of the Belgium-born Dutch astronomy professor M. Minnaert (author of ‘Light and Colour in the Open Air’). Historically, the best way is to call him either a ‘Dutch astronomer’ or a ‘Belgium-born Dutch astronomer’.
Published in Zenit 37, 185 in 2010
C. de Jager
C. de Jager, at the time Director of the Utrecht Observatory, shares his memories about the discovery of Nova Cygni. In the Dutch evening twilight, the Nova was first seen by  J.W. Schippers, G.P. Können and Gerard Peet – six hours after its first sight by K. Osada in Japan. In retrospect, we --  De Jager and the three official Dutch co-discoverers – have been privileged in have experienced the last echo of nineteenth-century astronomy.
Published in Private Document 2010/01 in 2010
G. P. Können
A simple argument shows that for a kinships farther away than 6 genetic steps the biological relation becomes negligible. This holds, among other examples, for third cousins and beyond, and for 7th or higher degree ancestors.
Published in Private Document 2010/02 in 2010
G. P. Können
The genetic relation between humans via their sex chromosomes differs from that via the other chromosomes. One of the consequences is that sisters are genetically more closely related with each others than with their mother or their own daugthers.
Published in IAU in 2009
At the IAU meeting of December 2009 Minor Planet 12157 (an asteroid) received the name Können, after me. Its diameter is about 5 km. Asteroid Können is at 2.4 AE from the sun and circles the sun in 3.75 year. The naming is formalized on 2 Dec 2009.
Published in Private Document 2005/01 (Eng) in 2005
G. P. Können
I was invited by ESA to stay at the European Space Operation Centre in Darmstadt (ESA-ESOC) during the landing of the Huygens Probe on Titan. The reason for the invitation was that I had contributed to the project by studying the possibility of Titan halos. Here I give some personal impressions of this experience.
Published in Gemini 20(12), 12-13 in 1988
G. P. Können and J. Tinbergen
An account is given about our attempts at La Palma Observatory to detect ice crystals in the Venus’s atmosphere, including the drawback of a temporary instrumental malfunction and our subsequent fortune that we got the opportunity to scan a terrestrial halo in a Venus-spoiling cirrus deck.