Anyone with a McCartan in their family tree is in  luck!  Thanks to the hard work of Nan Brennan and Deidre McEvoy much thorough research has been conducted and made available.  You can contact Nan and Deidre through the NIR-DOWN LIST if you find a connection to these families or have information to add.
If you had a DOWN McCartan that emigrated to the United States you might find some useful information on the McCARTAN CLIPPINGS page on the site.