Explanation to the astronomical ephemerides
The ephemerides contain a selection of ordinary phenomena of interest to observers: planetary phenomena, moon phases, lunar eclipses, and meteor showers. Some of the ephemerides are explained in their own sections:
Geocentric planetary phenomena
The geocentric planetary phenomena include the times for equinoxes and solstices.
The maximum elongations are the best epochs for inner planet observation, while the opposition dates provide the best circumstances for outer planets.
In the case of planet Mars, the best date is that of 'minimum distance', which in fact accounts for the instant where the light-time between the centers of Mars and the Earth is minimum; then, Mars's apparent diameter is greatest.
Timescales
Dates are given in Universal Time (UT) and (with the exception of those dates that include decimals, like the eclipse contacts) have not been rounded, but truncated. For example, a Moon's phase taking place at 23:53:59 UT is listed as 23:53 UT. Similarly, if a radiant's maximum occurs at 23 hours of day 18th, it is not rounded to 19th, but the 18th is given.
Universal Time is a scale based on Earth rotation, and the different local times are based on applying one or more timezones to it.