Robert Augustus Martin Born 1847 County Louth Then Went to Australia

I am trying to locate my great grandfather's history in Ireland. He was born in 1847 and went to Australia. I believe his mother may be a Catherine O'Connell. Today i saw a post from 10 years ago from a suemartin trying to locate the same person- her husband is a cousin of mine. They were wondering if Robert Augustus Martin got to Australia from America - This was ten years ago. I hope my cousins family are still alive now.