[1] In the Tholen classification, Sarpedon is similar to a dark D-type asteroid, though with an unusual spectrum (DU).
[5][4] In April 1996, a rotational lightcurve of Sarpedon was obtained from photometric observations by Italian astronomer Stefano Mottola at ESO's La Silla Observatory using the Bochum 0.61-metre Telescope.
[5][11] 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, Sarpedon measures between 77.48 and 108.21 kilometers in diameter and its surface has an albedo between 0.027 and 0.051.
[8][9][10] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.034 and a diameter of 94.63 kilometers based on an absolute magnitude of 9.41.
This minor planet was named from Greek mythology after the Lycian hero Sarpedon from the Iliad, who was killed by Patroclus, (617) during the Trojan War.