of beginning the new month on day 30withouta sighting, e.g. purely on the
basis of a new moon prediction, is apparently not considered.
Secondly, omen lists indicate that sometimes the new moon could be
sighted earlier, on days 29 or even 28 of the outgoing month (in which case,
the month presumably ran its course until the end of day 29, since months
could not be shorter than 29 days).^25 But our sources do not ever refer tofirst
sightings of the new moon on day 2 of the incoming month (or later). This
blatant asymmetry—which seems to imply that sightings on day 2 never
occurred—confirms that the month could not begin on a day before the new
moon had actually been sighted.^26
However, another body of sources from the same period, the letters of
astrologers to the king, suggest that the month was not solely determined by
new moon sighting, and that predictions could also be taken into account. The
following letter, from the Assyrian astrologer Bullut:u, presents the king with a
dilemma arising from the fact that the new moon had been predicted (or
rather was‘postdicted’)^27 to be visible on one evening, but was only actually
sighted on the next:
We watched on the 29th day;^28 the clouds were dense, we did not see the moon.We
watched on the 30th day; we saw the moon, (but) it was (already) very high. The
(weather) of the 29th day has to do with it.What is it that the king my lord says?^29(^25) The possibility of the new moon being sighted on the 29th or 28th of the month is
frequently implied in the astrological omen lists, e.g. Hunger (1992) nos. 14 (‘if the moon
becomes visible on the 28th day as if on the 1st day’), 63 (visible on the 28th), 457 (on the
29th); see also Huber (1982) 7, Beaulieu (1993) 86 n. 39, and Brown (2000) 146–8. An actual
sighting on the 29th, some time in the early 7th c., is reported in Hunger (1992) no. 457. In
another text, the Assyrian astrologer Nabû-ahhe-eriba reports that on the night following the
29th day (i.e. night of the 30th) he did not see the moon because of clouds, but on the night
following that, the moon looked like two days old (ibid. no. 79); this suggests that it should have
been visible two days earlier, on the night of the 29th.
(^26) The explanation is not simply that since the calendar month was based on sightings of the
moon, it never began on a day before the new moon wasfirst sighted. This, in fact, would not be
quite correct: for if—as is generally assumed—there was a rule that the month could not exceed
30 days, then there could have been cases where the new month began on day 31 even without
the moon being sighted (e.g. because of bad weather), and in such cases, the moon would have
first appeared on day 2 of the new month. The lack of references in omen lists tofirst new moon
sightings on the 2nd day suggests rather that the calendar month had ageneral tendencyof
beginning late in relation tofirst visibility of the new moon. This tendency is characteristic of
lunar calendars based on actual sightings of the new moon.
(^27) In this letter, it is actually a combination of prediction and postdiction. The attempt to sight
the moon at the end of the 29th implies that they predicted, to some extent, its visibility; then,
after observing the moon’s height at the end of the 30th, they postdicted that it should have been
visible the evening before.
(^28) This means at the end of the 29th day of the outgoing month (Astronomical Diaries and most
other sources would have called it the‘evening of the 30th’). For a similar usage in the neo-Assyrian
letters, see Parpola (1970–83) i, nos. 91, 96–9, 102, and his comment ibid. ii. 88 n. 179.
(^29) Parpola (1970–83) ii. 102 (with a judicious interpretation); Hunger (1992) no. 120;
Beaulieu (1993) 66–7 n. 4, whose translation is cited here.
The Babylonian Calendar 79