It was discovered by Swedish astronomer Claes-Ingvar Lagerkvist at the Australian Mount Stromlo Observatory near Canberra, on 19 April 1976.
[12] In April 2010, a rotational lightcurve of Wallenquist obtained by American astronomer Robert Stephens at the Goat Mountain Astronomical Research Station (GMARS, G79), California, gave a well-defined rotation period of 5.510 hours with a brightness amplitude of 0.22 magnitude (U=3).
[8][9] According to the surveys carried out by the Infrared Astronomical Satellite, IRAS, the Japanese Akari satellite, and the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Wallenquist measures between 21.1 and 27.6 kilometers in diameter while its surface has an albedo in the range of 0.08 and 0.15.
[4][5][6][7] The Collaborative Asteroid Lightcurve Link (CALL) derives an even lower albedo of 0.04 and calculates a diameter of 27.5 kilometer.
[2] After his retirement Wallenquist continued to research dark matter in open clusters at the Uppsala Astronomical Observatory.