It was discovered on 4 October 1978, by American astronomer Charles Kowal at the Palomar Observatory in California.
[1] The dark Jovian asteroid has a longer-than average rotation period of 26 hours and possibly an elongated shape.
[7] In September 2013, a rotational lightcurve of Acamas was obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California.
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Acamas measures 25.87 kilometers in diameter and its surface has an albedo 0.06,[6] while the Collaborative Asteroid Lightcurve Link assumes a standard albedo for a carbonaceous asteroid of 0.057 and calculates a diameter of 19.21 kilometers based on an absolute magnitude of 12.31.
[1] The name was suggested by Frederick Pilcher and published by the Minor Planet Center on 6 February 1993 (M.P.C.