It was discovered on 22 November 1979, by American astronomer Charles Kowal at the Palomar Observatory in southern California, United States.
[21] A large number rotational lightcurves have been obtained since December 1991,[5] when Alcathous was first observed by Stefano Mottola with the Loiano 1.52-meter telescope at Bologna Observatory, Italy.
[17] Several photometric observations between 2010 and 2017, by Daniel Coley and Robert Stephens at the Center for Solar System Studies and at GMARS (G79), also include the so-far best-rated period of 7.689 hours with a brightness amplitude of 0.22 magnitude (U=2+/3-/3/3/3-).
[8][9][10] The Collaborative Asteroid Lightcurve Link adopts the results obtained by IRAS, that is, an albedo of 0.0471 and a diameter of 114.63 kilometers based on an absolute magnitude of 8.64.
This minor planet was named after Alcathous, brave and handsome Trojan leader in Homer's Iliad.