1272 Gefion

1272 Gefion, provisional designation, is a stony asteroid and parent body of the Gefion family from the central region of the asteroid belt, approximately 7 kilometers in diameter. It was discovered on 10 October 1931, by astronomer Karl Reinmuth at the Heidelberg Observatory in Germany. The asteroid was named after Gefjon from Norse mythology.

Orbit and classification
Gefion is the namesake and parent body of the Gefion family (516), a large family of stony asteroids in the intermediate main belt. The family is also a suspected source of the L chondrites, common group of meteorites.

It orbits the Sun in the central main-belt at a distance of 2.4–3.2 AU once every 4 years and 8 months (1,697 days; semi-major axis of 2.78 AU). Its orbit has an eccentricity of 0.15 and an inclination of 8° with respect to the ecliptic.

The asteroid was first identified as at Heidelberg in September 1917. The body's observation arc begins at Heidelberg, six days after its official discovery observation.

Physical characteristics
In the SMASS classification, Gefion is a Sl-subtype that transitions from the common stony S-type asteroids to the rather rare L-types.

Rotation period
In 2010 and 2011, two rotational lightcurves of Gefion were obtained from photometric observations in the R-band by astronomers at the Palomar Transient Factory in California. Lightcurve analysis gave a rotation period of 2.900 and 3.087 hours with a brightness amplitude of 0.22 and 0.20 magnitude, respectively (U=2/2).

Diameter and albedo
According to the survey carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer, Gefion measures between 6.965 and 7.016 kilometers in diameter and its surface has an albedo between 0.2489 and 0.252. The Collaborative Asteroid Lightcurve Link assumes a standard albedo for carbonaceous asteroids of 0.057 and consequently calculates a much larger diameter of 12.62 kilometers based on an absolute magnitude of 13.22.

Naming
This minor planet was named after Gefjon a goddess in Norse mythology. It is also named for the Gefion Fountain in Copenhagen, Denmark. The official naming citation was mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 117).