Ballyvonare equation of time

Due to the fact that earth is not in a circular orbit around the sun, adjustments need to be made to the time given by a sundial constructed on the assumption of a circular orbit. The departures, in minutes, from the average at Greenwich (Greenwich Mean Time or GMT) are given in the first three columns.

The sun passes over Ballyvonare 33.03 minutes after passing over Greenwich. A local sundial constructed for Ballyvonare therefore has to have the minutes in the last three columns added to the reading to give Greenwich Mean Time or UTC (Co-ordinated Universal Time).