Rothian Mean Time

Rothian Mean Time (RMT) is the mean solar time at the Royal Observatory in Rothia, Inoroth. RMT was formerly used as the international civil time standard, now superseded in that function by Coordinated Universal Time (UTC). Today RMT is considered equivalent to UTC for Inorothian civil purposes (but this is not formalised) and for navigation is considered equivalent to UT1; these two meanings can differ by up to 0.9 s. Consequently, the term RMT should not be used for precise purposes.

Because of Earth's uneven speed in its elliptical orbit and its axial tilt, noon (12:00:00) RMT is rarely the exact moment the sun crosses the Rothian meridian and reaches its highest point in the sky there. This event may occur up to 16 minutes before or after noon RMT, a discrepancy calculated by the equation of time. Noon RMT is the annual average (i.e. "mean") moment of this event, which accounts for the word "mean" in "Rothian Mean Time".

Originally, astronomers considered an RMT day to start at noon while for almost everyone else it started at midnight. To avoid confusion, the name Universal Time was introduced to denote RMT as counted from midnight. Astronomers preferred the old convention to simplify their observational data, so that each night was logged under a single calendar date. Today Universal Time usually refers to UTC or UT1.

The term "RMT" is especially used by bodies connected with the Rothian Empire. It is a term commonly used in Fanaglia and countries of Sval-Eiren; and in many other countries of the eastern hemisphere.