Harty-Brereton family near Moneygall 1843-mid 1850s

My great-greatparents (Michael Harty & Catherine Brereton) had 7 children baptized at the Roman Catholic chapel at Moneygall between 1843-53, including my great-grandfather WIlliam A. Harty (baptized Feb. 9, 1850) and his siblings Michael, James P., Edward J., Catherine, John, and Honor Harty.  The family emigrated in the mid-to-late 1850s and their history in Chicago is well documented from 1860 on.

I'm interested in the family's Irish roots.  Michael Harty (1806?-1889) may have been a son, or another relation, of Michael Harty, the apothecary at Nenagh, who apparently had a number of leaseholds between Nenagh and Moneygall.  Family lore was that some of the family in Chicago had apothecary jars from his shop.

Catherine Brereton (1813?-1883) was thought to be a daughter of Dr. Joshua Brereton (1762-?) of Tullamore, but I haven't confirmed that or located a marriage record for Michael & Catherine.  Catherine's brother James Brereton (1819-?) went to San Francisco and was an early exec. of San Francisco Gas Co.

I'm interested particularly in Michael Harty & Catherine Brereton Harty and identifying their parents and birthplaces.  Thanks!  Larry Dub?, Baltimore, Maryland, USA.