Editing Maya calendar (section)

==Supplementary Series==
Many Classic period inscriptions include a series of glyphs known as the Supplementary Series. The operation of this series was largely worked out by [[John E. Teeple]]. The Supplementary Series most commonly consists of the following elements:

===Lords of the Night===
{{Main|Lords of the Night}}
Each night was ruled by one of the nine lords of the underworld. This nine-day cycle was usually written as two glyphs: a glyph that referred to the Nine Lords as a group, followed by a glyph for the lord that would rule the next night.

===Lunar Series===
A lunar series generally is written as five glyphs that provide information about the current [[New moon|lunation]], the number of the lunation in a series of six, the current ruling lunar deity and the length of the current lunation.

===Moon age===
The Maya counted the number of days in the current lunation. They used two systems for the zero date of the lunar cycle: either the first night they could see the thin crescent moon or the first morning when they could not see the waning moon.<ref>Thompson, J. Eric S. Maya Hieroglyphic Writing, 1950 Page 236</ref> The age of the moon was depicted by a set of glyphs that mayanists coined glyphs D and E:

* A new moon glyph was used for day zero in the lunar cycle.
* D glyphs were used for lunar ages for days 1 through 19, with the number of days that had passed from the new moon.
* For lunar ages 20 to 30, an E glyph was used, with the number of days from 20.

===Count of Lunations===
The Maya counted the lunations. This cycle appears in the lunar series as two glyphs that modern scholars call the 'C' and 'X' glyphs. The C glyph could be prefixed with a number indicating the lunation. No prefixing number meant one, whereas the numbers two through six indicated the other lunations.<ref>Teeple 1931:53</ref><ref>Thompson Maya Hieroglyphic Writing 1950:240</ref> There was also a part of the C glyph that indicated where this fell in a larger cycle of 18 lunations. Accompanying the C glyph was the 'X' glyph that showed a similar pattern of 18 lunations.<ref>Linden 1996:343–356.</ref><ref>Schele, Grube, Fahsen 1992</ref>

===Lunation length===
The present era lunar synodic period is about 29.5305877 [[Mean solar time|mean solar days]] or about 29 days 12 hours 44 minutes and 2+<sup>7</sup>/<sub>9</sub> seconds. As a whole number, the number of days per lunation will be either 29 or 30 days, with the 30-day intervals necessarily occurring slightly more frequently than the 29-day intervals. The Maya wrote whether the lunar month was 29 or 30 days as two glyphs: a glyph for lunation length followed by either a glyph made up of a moon glyph over a bundle with a suffix of 9 for a 29-day lunation or a moon glyph with a suffix of 10 for a 30-day lunation. Since the Maya didn't use fractions, lunations were approximated by using the formula that there were 149 lunations completed in 4400 days, which yielded a rather short mean month of exactly <sup>4400</sup>/<sub>149</sub> = 29+<sup>79</sup>/<sub>149</sub> days = 29 days 12 hours 43 minutes and 29+<sup>59</sup>/<sub>149</sub> seconds, or about 29.5302 days.<ref>Teeple 1931:67</ref>