20. Lagtime

The data recorded about the first day of the month includes lagtime, a measure of the time between sunset and moonset. Diary No. -567 Line 12 notes, it (the crescent) was thick; sunset to moonset: 20°.

The 20° lunar lagtime corresponds to 80 minutes (1° is equivalent to 4 minutes, 15° to an hour, 360° to a day.) Thus, according to the Diaries, the moon set 80 minutes after the sun disappeared over the horizon.