Andrew Graham (8 April 1815 – 5 November 1908) was an Irish

astronomer An astronomer is a scientist in the field of astronomy who focuses on a specific question or field outside the scope of Earth. Astronomers observe astronomical objects, such as stars, planets, natural satellite, moons, comets and galaxy, galax ...

, orbit computer and discoverer of the asteroid 9 Metis."Report of the Observatory Syndicate on the Chief Assistant at the Observatory." Cambridge, England: Cambridge University, 23 May 1903.

Astronomer at Markree, County Sligo

In 1842 Graham was appointed to work at Markree Observatory in

County Sligo County Sligo ( , ) is a Counties of Ireland, county in Republic of Ireland, Ireland. It is in the Northern and Western Region and is part of the Provinces of Ireland, province of Connacht. Sligo is the administrative capital and largest town in ...

in northwest

Ireland Ireland (, ; ; Ulster Scots dialect, Ulster-Scots: ) is an island in the North Atlantic Ocean, in Northwestern Europe. Geopolitically, the island is divided between the Republic of Ireland (officially Names of the Irish state, named Irelan ...

. The observatory had been established in 1830 by Colonel Edward Joshua Cooper (1798–1863) as a private institution on his country estate. Cooper equipped it with excellent astronomical instruments. Graham proved an energetic observer at Markree. Graham discovered the asteroid

9 Metis 9 Metis is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a ...

from Markree on 25 April 1848 while observing with a 3-inch aperture wide-field telescope manufactured for comet searching by the German instrument maker Ertel. Only eight minor planets were known before then, with the first four having been found in the period 1801–1807, and Graham's discovery consequently attracted considerable attention. His mathematical abilities allowed him to compute the orbit of the minor planet and to predict its apparent position into the future, including the gravitational effects of planets on its orbit around the Sun. Graham later worked on the Markree Catalogue, which consisted of observations of about sixty thousand stars along the

ecliptic The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making. Fr ...

taken between 8 August 1848 and 27 March 1856, and was published in four volumes in the years 1851, 1853, 1854 and 1856 respectively. Whilst working on this, he developed the square-bar micrometer, which greatly increased the efficiency of determining positions (

right ascension Right ascension (abbreviated RA; symbol ) is the angular distance of a particular point measured eastward along the celestial equator from the Sun at the equinox (celestial coordinates), March equinox to the (hour circle of the) point in questio ...

and

declination In astronomy, declination (abbreviated dec; symbol ''δ'') is one of the two angles that locate a point on the celestial sphere in the equatorial coordinate system, the other being hour angle. The declination angle is measured north (positive) or ...

) of celestial objects. Graham calculated the orbits of a large number of comets. These were used in his employer's book ''Cometic Orbits''. Graham resigned from his position at Markree and began new employment in Cambridge in March 1864.

Assistant at the Cambridge Observatory

Graham worked as First Assistant at the Cambridge Observatory, England, from 1864 to 1903. There he worked on the Cambridge Zone Catalogue, the Observatory's contribution to the catalogue of stars brighter than magnitude 9.5 organised by the

Astronomische Gesellschaft __NOTOC__ The ''Astronomische Gesellschaft'' is an astronomical society established in 1863 in Heidelberg, the second oldest astronomical society after the Royal Astronomical Society. History In 1882, the ''Astronomische Gesellschaft'' founded t ...

in Germany. This was in many ways an extension of his work at Markree, but for stars some distance to the north of the ecliptic. The catalogue of 14,464 stars between declinations 24° and 31° north was published in 1897. Graham collaborated with Anne Walker in the observing, who, although employed as a `lady computer' to perform routine mathematical calculations, regularly shared the observing tasks with Graham in a successful professional partnership. Graham retired from his post at the Cambridge Observatory in 1903 at the age of 88 years. He was granted a pension by the University of Cambridge. He died in Cambridge in 1908 aged 93 years.

References

{{DEFAULTSORT:Graham, Andrew 1815 births 1908 deaths 19th-century British astronomers Discoverers of asteroids Astronomers from Northern Ireland Scientists from County Fermanagh Recipients of the Lalande Prize