Both the UNSC and the Covenant use separate, though analogous, measurements to regulate and measure the passage of time and standardise the calendars of their interstellar territories.
“The Ross-Ziegler Blip was a stratigraphic event on Earth and a number of other colonized planets...Ross-Ziegler Blip
“A Cycle is a Covenant unit of time. It is one artificial day on High Charity. A cycle contains...Cycle
“The Military Calendar is the standard timekeeping calendar used by the UNSC and virtually all of...Military Calendar
“The Covenant battle calendar is the standardized timekeeping calendar employed by the Covenant...Covenant battle calendar