Dunsink is a townland

Townland

A townland or bally is a small geographical division of land used in Ireland. The townland system is of Gaelic origin—most townlands are believed to pre-date the Norman invasion and most have names derived from the Irish language...

 near Finglas

Finglas

-See also:* List of towns and villages in Ireland* List of abbeys and priories in Ireland...

, north Dublin, Ireland

Republic of Ireland

Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

.

Dunsink has an important observatory

Dunsink Observatory

The Dunsink Observatory is an astronomical observatory established in 1785 in the townland of Dunsink near the city of Dublin, Ireland.Its most famous director was William Rowan Hamilton, who, amongst other things, discovered quaternions, the first non-commutative algebra, while strolling from the...

, where William Rowan Hamilton

William Rowan Hamilton

Sir William Rowan Hamilton was an Irish physicist, astronomer, and mathematician, who made important contributions to classical mechanics, optics, and algebra. His studies of mechanical and optical systems led him to discover new mathematical concepts and techniques...

 and Hermann Brück

Hermann Brück

Hermann Alexander Brück was a German-born astronomer who spent the great portion of his career in the United Kingdom.-Education:...

 were both directors. It is the oldest scientific institution in Ireland. Built in 1783-1785, the observatory houses a 12 inch (30 cm) refracting telescope which was built by Grubbs of Dublin using a French manufactured lens.

The 1880 Definition of Time Act set the official time in Ireland to be Dublin mean time. This was regarded to mean the time at Dunsink, which was about GMT-25m21. In 1916 another Act moved Ireland

Ireland

Ireland is an island to the northwest of continental Europe. It is the third-largest island in Europe and the twentieth-largest island on Earth...

 to Greenwich Mean Time

Greenwich Mean Time

Greenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is arguably the same as Coordinated Universal Time and when this is viewed as a time zone the name Greenwich Mean Time is especially used by bodies connected with the United...

. Dunsink time is mentioned five times in James Joyce's

James Joyce

James Augustine Aloysius Joyce was an Irish novelist and poet, considered to be one of the most influential writers in the modernist avant-garde of the early 20th century...

 novel, Ulysses

Ulysses (novel)

Ulysses is a novel by the Irish author James Joyce. It was first serialised in parts in the American journal The Little Review from March 1918 to December 1920, and then published in its entirety by Sylvia Beach on 2 February 1922, in Paris. One of the most important works of Modernist literature,...

.

The observatory is situated on a hill 8km northwest of Dublin's city centre, where the Astronomy section of the School of Cosmic Physics, in the Dublin Institute for Advanced Studies

Dublin Institute for Advanced Studies

The Dublin Institute for Advanced Studies Dublin, Ireland was established in 1940 by the Taoiseach of the time, Éamon de Valera under the . The Institute consists of 3 schools: The , the and the . The directors of these schools are currently Professor Werner Nahm, Professor Luke Drury and...

, is located.

Dunsink is also the site of a major unofficial Traveller

Irish Traveller

Irish Travellers are a traditionally nomadic people of ethnic Irish origin, who maintain a separate language and set of traditions. They live predominantly in the Republic of Ireland, the United Kingdom and the United States.-Etymology:...

encampment, the subject of considerable media coverage in 2007.