Short answers, pulled from the story.
The Annals of Ulster were compiled in the late 15th century by the scribe Ruaidhrí Ó Luinín, working under his patron Cathal Óg Mac Maghnusa on Ballymacmanus Island (now Belle Isle) on Lough Erne in Fermanagh. Later scribes added entries extending the record to 1540 AD.
The Annals of Ulster span entries from 431 AD to 1540 AD. Entries up to 1489 were compiled by Ruaidhrí Ó Luinín; subsequent entries to 1540 were added by later hands.
The original manuscript of the Annals of Ulster is held at the Library of Trinity College, Dublin. A contemporary copy that fills gaps in the original is preserved at the Bodleian Library in Oxford.
The Annals of Ulster were written primarily in the Irish language, with some entries in Latin. Because earlier sources were copied verbatim, the text is also a valuable resource for linguists studying the evolution of the Irish language.
The Annals of Ulster first mention the Norse in 794, one year after the raiding of Lindisfarne. The text records Viking raiding, slave-taking, and the establishment of a permanent base at Dublin by 841, while also noting that Norse groups frequently allied with Irish factions against other Irish factions.
There are two main modern English translations: one by Mac Airt and Mac Niocaill published in 1983, and an earlier edition by MacCarthy published in 1895. MacCarthy's edition spans four volumes and covers the years 431 AD to 1540 AD.