Analysis of information sources in references of the Wikipedia article "Geta (emperor)" in English language version.
The notoriously unreliable Historia Augusta suggests Geta was born in May [27th] of 189. However, other more reliable sources are available for determining Geta's date of birth.
Publius Septimius Geta was the younger son of Septimius Severus. He was likely born in Rome—Milan has also been proposed—in March of 189.
Roxan no. 191 shows that Geta was already Augustus and trib. pot. II on 7 January 210. The tribunicia potestas was renewed every 10 December.
There is conflicting evidence concerning the exact date of Geta's murder. T. D. Barnes, has demonstrated that 26 December is almost certainly correct, ([The Sources of the Historia Augusta] 1978) 51-2.