It was discovered by Canadian-American astronomer J. C. Watson on August 15, 1868,[4] and was named after Helen of Troy in Greek mythology.

Radar observations were made of this object on Oct 7 and 19, 2001 from the Arecibo Observatory.

Analysis of the data gave an estimated ellipsoidal diameter of 71×63×63 ± 16% km.

The mean diameter estimated from IRAS infrared measurements is 66 km, in agreement with the radar findings.

It is classified as an S-type asteroid in the Tholen system,[3][5] suggesting a predominantly silicate composition.