Irish Passenger Lists, 1847-1871
Although ACOM gives no decription of the dataset, it is evidently taken from the lists that were developed from the order books of two main passenger lines operating out of Londonderry--J.& J. Cooke (1847-67) and William McCorkell & Co. (1863-71).
Although they were transcribed under the auspices of the Northern Ireland Department of Economic Development, they were actually published in 1988 by the Genealogical Publishing Co. of Baltimore, MD.
This situation is exactly analogous to the dataset "Emigrants from England to the American Colonies, 1773-1776" It was compiled by Peter Wilson Coldham in Surrey in 1988 and published by Genealogical Publishing Co. of Baltimore, MD. It is available to US Deluxe members in the Immigtation Collection.