Next: Determination of Julian Day
Following modern astronomical practice, in this treatise we shall specify dates
by means of Julian day numbers. According to this
scheme, days are numbered consecutively from January 1, 4713 BCE, which
is designated day zero. For instance, October 14, 1066 CE (the date of the battle of Hastings) is
day 2110701. Each Julian day commences at 12:00 universal time (UT).