182 Elsa is a Main belt asteroid that was discovered by Johann Palisa on February 7, 1878. The origin of the name is uncertain; it may be named after the character in the legend of Lohengrin perpetuated by Richard Wagner's opera of the same name. Based upon its spectrum, it is classified as a stony S-type asteroid.
It rotates very slowly; in 1980 its rotation period (or "day") was estimated to be about 3.3 Earth days. In 2008, a collaborative effort from three different sites was used to build a complete light curve for the asteroid, which showed a period of 80.088 ± 0.002 hours with a brightness variation of 0.30 ± 0.03 in magnitude. A possible companion has been proposed to explain the slow rotation.
Elsa has very amplified lightcurve indicating an elongated or irregular body. It was one of five minor planets included in the 1993 study, Transition Comets -- UV Search for OH Emissions in Asteroids, which was research involving amateur astronomers who were permitted to make use of the Hubble Space Telescope.
During 2002, 109 Felicitas was observed by radar from the Arecibo Observatory. The return signal matched an effective diameter of 44 ± 10 km. This is consistent with the asteroid dimensions computed through other means.