Karl Schwarzschild, Annie J. Cannon, and Cornelis Easton: PhDs honoris
  causa of Jacobus C. Kapteyn
  Honorary degrees and particularly doctorates are important instruments to
enhance the standing of universities and professors, in addition to receiving
these as a measure of a scientist's recognition. Jacobus C. Kapteyn from the
University of Groningen in the Netherlands, one of the most prominent
astronomers of his times, received three of these and has persuaded his
university to award at least three, possibly five. I examine the background of
the selection of the latter in view of developments in Kapteyn's times in his
career, international astronomy and political and cultural circumstances.
