Kaj Strand was a Danish astronomer who began his research career working with Ejnar Hertzsprung (see Hertzsprung-Russell Diagram) using photography to measure precisely the relative motions of nearby stars. In 1938, Strand brought knowledge of the technique to Sproul Observatory where it was used in the search for exoplanets. Strand himself concentrated on 61 Cygni and, in 1943, announced that he had detected wobbles in the movement of this binary star which indicated the presence of a planetary companion.¹

 

Reference

1. Strand K. "61 Cygni as a Triple System," Publications of the Astronomical Society of the Pacific, 55, 29 (1943).