It was discovered on 28 December 1940, by Finnish astronomer Yrjö Väisälä at Turku Observatory in Southwest Finland.

[13] Between 2000 and 2011, several rotational lightcurves of Punkaharju were obtained from photometric observations by astronomers Brian Warner and Pierre Antonini.

[8][9][11] In addition, a concurring period of 5.01327 hours was published in 2016, using the Uppsala Asteroid Photometric Catalogue as the main-data source.

[10] French CCD-specialist Cyril Cavadore also derived a less secure period of 5.028 hours from his observations in October 2005 (U=2-).

[5][6][7] The Collaborative Asteroid Lightcurve Link derives an albedo of 0.196 and a diameter of 31.41 kilometers using an absolute magnitude of 9.9.