James McMahon is an American

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

 amateur astronomer

Amateur astronomy

Amateur astronomy, also called backyard astronomy and stargazing, is a hobby whose participants enjoy watching the night sky , and the plethora of objects found in it, mainly with portable telescopes and binoculars...

, acknowledged for his visual observations

Observational astronomy

Observational astronomy is a division of the astronomical science that is concerned with getting data, in contrast with theoretical astrophysics which is mainly concerned with finding out the measurable implications of physical models...

 of asteroid

Asteroid

Asteroids are a class of small Solar System bodies in orbit around the Sun. They have also been called planetoids, especially the larger ones...

 occultation

Occultation

An occultation is an event that occurs when one object is hidden by another object that passes between it and the observer. The word is used in astronomy . It can also refer to any situation wherein an object in the foreground blocks from view an object in the background...

s. In 1978 his observation of the occultation of the asteroid 532 Herculina

532 Herculina

- Discovery :It was discovered on April 20, 1904, by Max Wolf in Heidelberg, and initially catalogued as 1904 NY. The origin of its name is not known; it may be named after the mythical Hercules, or after an unknown woman of that name...

 with the star SAO 120774, together with photometric study made at the Lowell Observatory

Lowell Observatory

Lowell Observatory is an astronomical observatory in Flagstaff, Arizona. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark in 1965....

, was considered a proof of the existence of a Herculina's natural satellite

Natural satellite

A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called its primary. The two terms are used synonymously for non-artificial satellites of planets, of dwarf planets, and of minor planets....

, which would be the first discovery of an asteroid moon

Asteroid moon

A minor planet moon is an astronomical body that orbits a minor planet as its natural satellite. It is thought that many asteroids and Kuiper belt objects may possess moons, in some cases quite substantial in size...

 in history. However, a 1993 Hubble Space Telescope

Hubble Space Telescope

The Hubble Space Telescope is a space telescope that was carried into orbit by a Space Shuttle in 1990 and remains in operation. A 2.4 meter aperture telescope in low Earth orbit, Hubble's four main instruments observe in the near ultraviolet, visible, and near infrared...

 observation failed to confirm the discovery. In 1979 James MacMahon was the first person awarded with the newly established Amateur Achievement Award of the Astronomical Society of the Pacific

Astronomical Society of the Pacific

The Astronomical Society of the Pacific is a scientific and educational organization, founded in San Francisco on February 7, 1889. Its name derives from its origins on the Pacific Coast, but today it has members all over the country and the world...

.