Dear Colleen
Welcome to Ireland Reaching Out and apologies for the delay in replying to your message.
As you can see from the link below, Ardcarn is a Civil Parish in Co. Roscommon:
http://www.irishtimes.com/ancestor/fuses/townlands/index.cfm?fuseaction=TownlandsInCivil&civilparishid=2024&civilparish=Ardcarn&citycounty=Roscommon
Records for the corresponding Roman Catholic Parish of Cootehall begin in 1843 with some missing marriage records between 1860 and 1861.As this is the case, there will be no church records for John and Rose and any of their children, if in fact, they were living in this parish.
Other important sources include the Tithe Applotment Books and Griffith?s Valuation. Even though these sources only record the head of the household, the information is very important and can be valuable:
Tithe Applotment Books (1823-1837): http://titheapplotmentbooks.nationalarchives.ie/search/tab/index.jsp
Griffith?s Valuation (1847-1864): http://www.askaboutireland.ie/griffith-valuation/
The National Archives of Ireland: http://www.census.nationalarchives.ie/search/ you can search the 1901/1911 Census on the National Archives page too, for instances of the family name at that time
Remember to post any new information that you find here. The more information you post, the more likely it is that one of our volunteers will be able to advise or assist you. Also include information concerning which sources you may have already used so others may further your search.
Best of luck with your search
Clare Doyle
Genealogy Support