I don't know of any Bridget Gehan in my Gehan ancestors but I have run across these in my searchings:
1860 Columbia County, New York Census
Ghent, page 744
James Gehan, age 38, farm laborer, born Ireland
wife Hannah, age 36, born Ireland
son Michael, age 8, born NY
son James, age 7, born NY
daughter Bridget, age 6, born NY
son Thomas, age 4, born NY
son Joseph, age 1, born NY
son Christopher, age 4/12, born NY
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1870 Columbia County, New York Census
Ghent, page 270, line 11
GAHEN, James, age 55, works on railroad, born Ireland
wife Hannah, age 45, born Ireland
son Michael, age 19, born NY, works on railroad
son James, age 18, born NY, laborer
son Thomas, age 14, born NY
son Joseph, age 12, born NY
son Christopher, age 10, born NY
daughter Anna, age 8, born NY
daughter Mary, age 6, born NY
son John, age 3, born NY
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1880 Litchfield County, Connecticut Census
Enumeration District 5, Sheet 20, line 49
Gahen, James, age 63, born Ireland
wife Hannah, age 57, born Ireland
daughter Anna, age 18, born New York
daughter Mary, age 16, born New York
son John, age 11, born New York
daughter Bridget, age 9, born New York
son Thomas, age 23, born New York
These seem to be the same family, ages are off some from census to census but children's names seem to match up.
Also, the Ontario, Canada 1871 Census has Bridget Gehan, born 1868 in Ontario. Parents were Patrick and Bridget Gehan, both born in Ireland.