Mesoamerican Long Count calendar number (portion of the DN preceding era date) 7.2.14.19<br> Add Ring number to the ring number date to reach 13.0.0.0.0 Thompson contains a table of typical long reckonings after Satterwaite. The "Serpent Numbers" in the Dresden codex pp. 61–69 is a table of dates using a base date of 1.18.1.8.0.16 in the prior era (5,482,096 days). Mesoamerican Long Count calendar The Mesoamerican Long Count calendar is a non-repeating, vigesimal (base-20) and base-18 calendar used by several pre-Columbian Mesoamerican cultures, most notably the Maya. For this reason, it is often known as the Maya (or Mayan) Long Count calendar. Using a
Mesoamerican Long Count calendar The number of leap days, keeping in mind that the year 600 is not a leap year, is 10. Subtracting that from 317 remainder days is 307; in other words, the 307th day of the year 644 AD, which is November 3. To summarize: the Long Count date 9.10.11.17.0 corresponds to November 3, 644 AD, in the "Proleptic Gregorian calendar". To convert a Julian day to a Julian/Gregorian astronomical date (Proleptic Julian calendar before 46 BC): Use an astronomical algorithm such as the "Method of Meeus" to convert the Julian day to a Julian/Gregorian date with astronomical dating of negative