Q:Information: - In physics, an orbit is the gravitationally curved path of an object around a point in space, for example the orbit of a planet about a star or a natural satellite around a planet. Normally, orbit refers to a regularly repeating path around a body, although it may occasionally be used for a non recurring trajectory or a path around a point in space. To a close approximation, planets and satellites follow elliptical orbits, with the central mass being orbited at a focal point of the ellipse, as described by Kepler's laws of planetary motion. - Union Observatory also known as Johannesburg Observatory (078) is a defunct astronomical observatory in Johannesburg, South Africa that was operated between 1903 and 1971. It is located on Observatory Ridge, the city's highest point at 1,808 metres altitude in the suburb Observatory. - A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, and other trans-Neptunian objects. As of 2016, the orbits of 709,706 minor planets were archived at the Minor Planet Center, 469,275 of which had received permanent numbers ). - Harry Edwin Wood (3 February 1881 27 February 1946) was an English astronomer, director of the Union Observatory in Johannesburg, and discoverer of minor planets. - 790 Pretoria is a minor planet orbiting the Sun that was discovered by English astronomer Harry Edwin Wood on January 16 , 1912 . It is a member of the Cybele group located beyond the core of the main belt ( see Minor planet groups ) . 10 radiometric data collected from Kitt Peak in 1975 gave a diameter estimate of 175 km. In the present day it is estimated to be 170 km ( 106 mi ) in diameter . Photometric measurements of the asteroid made in 2005 at the Palmer Divide Observatory showed a light curve with a period of 10.370 0.002 hours and a brightness variation of 0.08 0.03 in magnitude . - The Minor Planet Center (MPC) is the official worldwide organization in charge of collecting observational data for minor planets (such as asteroids) and comets, calculating their orbits and publishing this information via the "Minor Planet Circulars". Under the auspices of the International Astronomical Union, it operates at the Smithsonian Astrophysical Observatory, which is part of the Center for Astrophysics along with the Harvard College Observatory. After reading the paragraphs above, we are interested in knowing the entity with which '790 pretoria' exhibits the relationship of 'site of astronomical discovery'. Find the answer from the choices below. Choices: - harvard college observatory - kepler - union observatory
A:
union observatory