(first centuryBCE), but it is quite possible that decisions were still taken by the
king or his administration. As we have seen above, there is at least some
evidence of this in the early Achaemenid period (late sixth centuryBCE). The
inconsistency of calendar month decisions (in cases of conflicts between
predictions and sightings) suggests that although the Babylonian month was
considerably more regular in relation to the new moon than it had been in the
neo-Assyrian period, it was stillflexible and subject to a measure of political
control.^73
Summary and discussionThe Babylonian month began, in principle, on the evening offirst visibility of
the new moon, although deviations of one day on either side were not
uncommon. These deviations would not have affected the generally lunar
and astronomical character of the Babylonian calendar, but the precise begin-
ning of the month would have remained often unpredictable. There was
certainly no regular pattern or calendrical scheme.
Astrological omen lists from the neo-Assyrian period (eighth-seventh cen-
turies) suggest that the beginning of the month was based solely on new moon
sightings, although letters of astrologers from the same period indicate that
attempts were being made to legitimize the use of new moon predictions (or
postdictions). By the Achaemenid period and later (sixth–first centuriesBCE),
new moon prediction had become a legitimate way of setting the beginning of
the month. This had the effect of improving the month’s conformity to the
evening offirst visibility of the new moon, and thus of regularizing the
Babylonian calendar.
In the neo-Assyrian period, but probably also in later periods, new moon
sightings and predictions were made by astrologers who conveyed the relevant
information to the king. In cases of uncertainty—e.g. when the new moon was
sighted one day later than predicted—the king decided when the new month
began. Thus in spite of its relative astronomical regularity, the beginning of the
month remained under the king’s control. It is unclear whether the king
remained personally involved in this process in the later periods (especially
in the Seleucid and Parthian periods), but the inconsistent resolution of
conflicts between prediction and sighting in the later periods suggests that
someflexibility remained.
The evolution of a calendar based on new moon sighting alone (in the neo-
Assyrian period) to one based on a combination of new moon prediction and
(^73) Furthermore, the inconsistent, apparently random character of these decisions confirms
perhaps that we are dealing with a real-life calendar, rather than with a theoretical calendar of
astronomers: see discussion above, near n. 10.
92 Calendars in Antiquity