865 Zubaida

865 Zubaida is an elongated, stony background asteroid from the inner regions of the asteroid belt. It was discovered on 15 February 1917, by astronomer Max Wolf at the Heidelberg Observatory in southwest Germany, and given the provisional designations and. The uncommon L-type asteroid has a rotation period of 11.4 hours and measures approximately 17 km in diameter. It was named after Zobeide, a character in the opera Abu Hassan by Carl Maria von Weber (1786–1826).

Orbit and classification
Zubaida is a non-family asteroid of the main belt's background population when applying the hierarchical clustering method to its proper orbital elements. It orbits the Sun in the inner asteroid belt at a distance of 1.9–2.9 AU once every 3 years and 9 months (1,373 days; semi-major axis of 2.42 AU). Its orbit has an eccentricity of 0.19 and an inclination of 13° with respect to the ecliptic. The body's observation arc begins with its first observation as at Heidelberg Observatory on 29 November 1908, more than 8 years prior to its official discovery observation.

Naming
This minor planet was named after the character Zobeide, the Caliph's wife in the opera Abu Hassan by German composer Carl Maria von Weber (1786–1826). The official was also mentioned in The Names of the Minor Planets by Paul Herget in 1955 (H 85). Another asteroid, 866 Fatme, was also named after one of the characters of this opera. The composer himself was honored with the naming of 4152 Weber.

Physical characteristics
In the SDSS-based taxonomy (MOC), Zubaida is an uncommon L-type asteroid, while in the Masi Foglia Binzel (MFB) taxonomic variant, it is a common, stony S-type asteroid.

Rotation period
In January 2007, a rotational lightcurve of Zubaida was obtained from photometric observations by Colin Bembrick at the Mount Tarana Observatory and Greg Crawford at Bagnall Beach Observatory  in collaboration with two other Australian observers. Lightcurve analysis gave a well-defined rotation period of $16.774 km$ hours with a brightness variation of $16.81 km$ magnitude (U=3). The observers also estimate an axial ratio (a/b) of 1.42 for the asteroid. An alternative observation during January 2007, by David Higgins and Julian Oey at Hunters Hill and Leura  observatories, respectively, gave a concurring period $17.77 km$ hours with an amplitude of $11.353 h$ magnitude (U=3–).

Diameter and albedo
According to the surveys carried out by the NEOWISE mission of NASA's Wide-field Infrared Survey Explorer (WISE), the Japanese Akari satellite, and the Infrared Astronomical Satellite IRAS, Zubaida measures ($0.097$), ($0.11$) and ($0.128$) kilometers in diameter and its surface has an albedo of ($11.353$), ($0.38$) and ($11.363$), respectively. The WISE team also published an alternative mean diameter of ($0.38$) with a corresponding albedo of ($16.774$). The Collaborative Asteroid Lightcurve Link assumes a standard albedo for a stony asteroid of 0.20 and calculates a diameter of 13.58 kilometers based on an absolute magnitude of 11.7.