53 Kalypso is a large and very dark main belt asteroid that was discovered by German astronomer Robert Luther on April 4, 1858, at Düsseldorf.

The orbit of 53 Kalypso places it in a mean motion resonance with the planets Jupiter and Saturn.

[8] Photometric observations of this asteroid during 2005–06 gave a light curve with a period of 18.075 ± 0.005 hours and a brightness variation of 0.14 in magnitude.

[9] In 2009, a photometric study from a different viewing angle was performed at the Organ Mesa Observatory in Las Cruces, New Mexico, yielding a rotation period of 9.036 ± 0.001 with a brightness variation of 0.14 ± 0.02 magnitude.

The author of the earlier study used additional data observation that favored the 9.036 hour period.