2046 Leningrad, provisional designation 1968 UD, is a carbonaceous Themistian 1 asteroid from the outer regions of the asteroid belt, approximately 24 kilometers in diameter. It was discovered on 22 October 1968, by Soviet astronomer Tamara Smirnova at the Crimean Astrophysical Observatory in Nauchnij, on the Crimean peninsula. The asteroid was named for the Soviet city of  Leningrad (now St. Petersburg).
Orbit and classification Leningrad is a member of the Themis family, a dynamical family of carbonaceous asteroids with nearly coplanar ecliptical orbits, located in the outer-belt main. It orbits the Sun at a distance of 2.6–3.7 AU once every 5 years and 7 months (2,048 days). Its orbit has an eccentricity of 0.18 and an inclination of 3 ° with respect to the ecliptic.
observation arc begins 39 years prior to its official discovery observation, with a precovery taken at Lowell Observatory in October 1929. One week later, the asteroid was identified as 1929 VK at Lowell Observatory.
In August 2012, a rotational
lightcurve of Leningrad was obtained from photometric observations by astronomers at the Oakley Southern Sky Observatory ( ). Lightcurve analysis gave a E09 rotation period of 5.296 hours with a brightness variation of 0.11 magnitude ( ). U=2+
Diameter and albedo
According to the surveys carried out by the Japanese
Akari satellite, and NASA's Wide-field Infrared Survey Explorer with its subsequent NEOWISE mission, Leningrad measures 23.968 and 27.67 kilometers in diameter and its surface has an albedo of 0.060 and 0.085, respectively.  
Collaborative Asteroid Lightcurve Link assumes a standard albedo for Themistian asteroids of 0.08 and calculates a diameter of 23.55 kilometers based on an absolute magnitude of 11.5.
minor planet was named for Saint Petersburg, the second largest city of Russia after Moscow. During the Soviet Union, the city was named "Leningrad" between 1924 and 1991. It was also called Petrograd during 1914–1924. The approved naming citation was published by the  Minor Planet Center on 1 April 1980 ( ). M.P.C. 5282
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"JPL Small-Body Database Browser: 2046 Leningrad (1968 UD1)" (2017-05-04 last obs.). Jet Propulsion Laboratory . Retrieved . 29 June 2017
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"LCDB Data for (2046) Leningrad". Asteroid Lightcurve Database (LCDB) . Retrieved . 29 June 2017
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Mainzer, A.; Grav, T.; Masiero, J.; Hand, E.; Bauer, J.; Tholen, D.; et al. (November 2011). "NEOWISE Studies of Spectrophotometrically Classified Asteroids: Preliminary Results". The Astrophysical Journal. 741 (2): 25. arXiv: . 1109.6407 Bibcode: 2011ApJ...741...90M. doi: 10.1088/0004-637X/741/2/90.
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Usui, Fumihiko; Kuroda, Daisuke; Müller, Thomas G.; Hasegawa, Sunao; Ishiguro, Masateru; Ootsubo, Takafumi; et al. (October 2011). "Asteroid Catalog Using Akari: AKARI/IRC Mid-Infrared Asteroid Survey". Publications of the Astronomical Society of Japan. 63 (5): 1117–1138. Bibcode: 2011PASJ...63.1117U. doi: 10.1093/pasj/63.5.1117 . Retrieved . 17 October 2019 ( online, AcuA catalog p. 153)
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Simpson, Gary; Chong, Elena; Gerhardt, Michael; Gorsky, Sean; Klaasse, Matthew; Kodalen, Brian; et al. (July 2013). "Asteroid Lightcurve Analysis at the Oakley Southern Sky Observatory: 2012 August - October". The Minor Planet Bulletin. 40 (3): 146–151. Bibcode: 2013MPBu...40..146S. ISSN 1052-8091 . Retrieved . 29 June 2017
Veres, Peter; Jedicke, Robert; Fitzsimmons, Alan; Denneau, Larry; Granvik, Mikael; Bolin, Bryce; et al. (November 2015). "Absolute magnitudes and slope parameters for 250,000 asteroids observed by Pan-STARRS PS1 - Preliminary results". Icarus. 261: 34–47. arXiv: . 1506.00762 Bibcode: 2015Icar..261...34V. doi: 10.1016/j.icarus.2015.08.007 . Retrieved . 29 June 2017
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