Egyptian Civil Calendar (Era of Nabonassar) (埃及民用曆)

THE ANCIENT EGYPTIAN CIVIL CALENDAR — the wandering year: twelve 30-day months in the three seasons of the Nile (Akhet the Inundation, Peret the Emergence, Shemu the Harvest) plus the FIVE EPAGOMENAL DAYS, the birthdays of the gods — Osiris, Horus the Elder, SET (the ill-omened day the hemerologies feared), Isis, Nephthys. 365 days EXACTLY, never a leap in three thousand years, drifting through the seasons in the 1,460-year SOTHIC CYCLE — and precisely that unbending simplicity made it THE timekeeping of ancient astronomy: Ptolemy dated the Almagest in it, on the ERA OF NABONASSAR (epoch 26 February 747 BC Julian, JDN 1448638, asserted against the shared Julian machinery). THE CENSORINUS LAW AT LOAD, antiquity's most famous calendrical anchor reproduced to the day: 1 Thoth of Nabonassar year 887 must equal Julian 20 JULY AD 139 — the civil new year meeting the heliacal rising of Sothis, 886 wandering years = 323,390 days exactly. THE 365-FAMILY LOCKSTEP PROVEN: the Armenian, Zoroastrian and Mandaean calendars share the leap-free year, and the constancy of their offsets is asserted against the Armenian engine directly. The Alexandrian reform of 25 BC — the Coptic engine's ancestor — is named. Egyptian becomes three systems. Pure compute, no LLM.

Cost: 1 TIAN Points per call. tRPC procedure egyptianCivil.day.