was a Dutch astronomer, a lifelong member of the scientific staff of the Leiden Observatory.
[2] Starting circa 1924, he studied Jupiter's Galilean satellites, minor planets, comets, and the proper motions of faint stars, in particular members of the Hyades cluster.
He computed orbital characteristics for many of the minor planets discovered by Hendrik van Gent.
[3] She, together with Jan Oort, published their work on the Hyades cluster in 1975, 9 years after his death, in the journal Astronomy and Astrophysics [1].
The main-belt asteroid 1667 Pels was named in his honour by discoverer and colleague Hendrik van Gent (M.P.C.