What is "julian epoch"

Julian \Jul"ian\ (?; 277)

1. [L. Julianus, fr. Julius. Cf. July, Gillian.] Relating to, or derived from, Julius C[ae]sar.

   Julian calendar, the calendar as adjusted by Julius C[ae]sar, in which the year was made to consist of 365 days, each fourth year having 366 days.

   Julian epoch, the epoch of the commencement of the Julian calendar, or 46

3. Julian period, a chronological period of 7,980 years, combining the solar, lunar, and indiction cycles (28 x 19 x 15 = 7,980), being reckoned from the year 4713 B. C., when the first years of these several cycles would coincide, so that if any year of the period be divided by 28, 19, or 15, the remainder will be the year of the corresponding cycle. The Julian period was proposed by Scaliger, to remove or avoid ambiguities in chronological dates, and was so named because composed of Julian years.

   Julian year, the year of 365 days, 6 hours, adopted in the Julian calendar, and in use until superseded by the Gregorian year, as established in the reformed or Gregorian calendar.