I found the civil marriage record form Thomas Geoghegan and Mary Kelly at the free irishgenealogy.ie website. This marriage record, unlike the church marriage record you supplied as an attachment, shows the couple were married on January 28, 1866, instead of December 28, 1866. This mans the registrar who recorded the civil marriage, Robert Willis, was off on the date of the marriage by exactly one month.
The marriage record for Thomas and Mary is attached, and further shows that Thomas was a 28 year old bachelor before he married and that his residence at the time of marriage was “Russeen,” which is actually spelled, “Rusheen.” Thomas’s occupation was farmer. His father is also recorded as Thomas Geoghegan, a farmer.
The marriage record also shows that Mary was a 23 year old spinster when she married and that her residence was also “Russeen.” Her father is William Kelly, a farmer. The priest who married Thomas and Mary in the Catholic Chapel of Oughterard was John Dooly. The witnesses were Bartly Fahy and Mary Geoghegan. The witness Mary Geoghegan as well as Thomas Geoghegan and Mary Kelly signed the marriage register with an X, which is an indication they could not write. The marriage is the last record in the marriage register.
Finding the civil birth record for Thomas and Mary’s son Thomas at irishgenealogy.ie was a little more challenging, but after some time found an index of his birth that I thought could pertain to him. The index spells his last name as, “Houghegan,” rather than Geoghegan.
The index of Thomas’s birth, from irishgenealogy.ie, is below:
Name THOMAS HOUGHEGAN
Date of Birth 1866
Group Registration ID 7924902
SR District/Reg Area Oughterard
Mother's Birth Surname N/R
Attached to the index is a copy of the original civil birth record for Thomas Houghegan, showing he was born in “Rushinny,” (which I believe should also be Rusheen), on 22 November 1866. His father is Thomas Houghegan, a farmer residing in Rushinny. Thomas’s mother is Mary Houghegan, formerly Kelly. The father Thomas, reported the birth to the local registrar, R. Willis, who recorded the birth on 27 November 1866. Thomas’s birth record is Number 428 in the death register, and is attached to this reply.
Your information shows that Thomas’s mother Mary died giving birth, and so I looked for her death at irishgenealogy.ie. Unlike birth and marriage records however, irishgenealogy.ie has only digitized death records from the year 1878, but they have indexed death s for all of Ireland from the year 1864.
Knowing that Mary would have died soon after Thomas was born, I also found her death index under the last name of “Houghegan.” The index gives her year of death as 1867 and her age at death as 26. The index is below:
Name MARY HOUGHEGAN
Date of Death 1867
Group Registration ID N/R
SR District/Reg Area Oughterard
Deceased Age at Death 26
Returns Year 1867
Returns Quarter 1
Returns Volume No 4
Returns Page No 335
You can order Mary’s death cert from the General Register Office (GRO). For costs and information on how to order birth, marriage, and death certs from the GRO, go to: https://www.irishgenealogy.ie/en/civil-records/help/i-want-to-get-a-copy...