CALHOUN, John left Londonderry?

[Rozzy]

My ancestor John Calhoun, son of John and Lavinia (Reid)  Calhoun,
born 1828/30 in Londonderry, left Londonderry and arrived in Melbourne
Australia in 1847/55 (from various sources).

I am trying to track when he was actually born, when he left, and where he went on the way to Australia.

Any ideas please?

Thanks,

Rozzy

[Rozzy]

Hi, I have further information from another thread, thanks to Jean.

A John Calhoun, aged 20, arrived in USA from Londonderry in May 1851,
on the "Hannah Kerr". 

This age is close, and as he's under 21, would there be any records
of his parent's details so I could see if he's mine please?

Thanks,

Rozzy