43. Other times
Enuma Anu Enlil and MUL.APIN are two sizable compendiums of astronomical records and related texts. Historians date the records mostly to the centuries and millennia before 747 BC. But like the Venus Tablet, the observations do not tally with conventional computations. Their primary purpose may be divinatory rather than astronomical, or as some historians hold, the observations may simply be crude.
The compendiums draw on an ideal calendar that rounds off the year to 360 days and the month to 30 days. If early Babylonian astronomy were based on an inaccurate month and year, then standard calculations would be ineffective in dating the observations recorded in the ancient documentation.
36. Egypt, an absolute date
A Babylonian-Egyptian double date found on a papyrus is the earliest absolute Egyptian date. It corresponds to 2 November 473 BC. From that time on, the correlation between the Babylonian and Egyptian calendars appears satisfactory.
Ptolemy was still using the Egyptian calendar 600 years later. Though he lived near Alexandria, astronomical data from pre-Hellenistic Egypt is conspicuously absent from his work. Worthwhile ancient Egyptian observations were unavailable in his day and they remain scarce today.
35. Egypt, a hoary old chronology
The history of the civilization along the Nile reaches back beyond 2500 BC. The astronomical contribution to this long drawn out timeline is based on the Sothic Hypothesis, which assumes the Egyptian calendar continued undisturbed for millenia.
The permanence of the Egyptian calendar has not been substantiated. Hence calendar dates earlier than the 6th century BC cannot be considered astronomically validated.