Editing Maya calendar (section)

==Overview==
{{Further|Maya astronomy}}
The Maya calendar consists of several  cycles or ''counts'' of different lengths. The 260-day count is known to scholars as the ''[[Tzolkʼin|Tzolkin]]'', or ''Tzolkʼin''.<ref name="Academia">{{cite book |author=Academia de las Lenguas Mayas de Guatemala |date=1988 |title=Lenguas Mayas de Guatemala: Documento de referencia para la pronunciación de los nuevos alfabetos oficiales |publisher=Instituto Indigenista Nacional |location=Guatemala City}} For details and notes on adoption among the [[Mayanist]] community, see Kettunen & Helmke (2020), p. 7.</ref> The Tzolkin was combined with a 365-day vague solar year known as the [[Haabʼ]] to form a synchronized cycle lasting for 52 Haabʼ called the [[Calendar Round]]. The Calendar Round is still in use by many groups in the Guatemalan highlands.<ref>Tedlock (1992), p. 1</ref>

A different calendar was used to track longer periods of time and for the inscription of [[calendar date]]s (i.e., identifying when one event occurred in relation to others). This is the [[Mesoamerican Long Count calendar|Long Count]]. It is a count of days since a mythological starting-point.<ref>"Mythological" in the sense that when the Long Count was first devised sometime in the Mid- to Late Preclassic, long after this date; see e.g. Miller and Taube (1993, p.&nbsp;50).</ref> According to the correlation between the Long Count and Western calendars accepted by the great majority of Maya researchers (known as the Goodman-Martinez-Thompson, or GMT, correlation), this starting-point is equivalent to August 11, 3114&nbsp;BC in the [[proleptic Gregorian calendar]] or September 6, in the [[Julian calendar]] (−3113 astronomical). The GMT correlation was chosen by [[J. Eric S. Thompson|John Eric Sydney Thompson]] in 1935 on the basis of earlier correlations by [[Joseph T. Goodman|Joseph Goodman]] in 1905 (August 11), Juan Martínez Hernández in 1926 (August 12) and Thompson himself in 1927 (August 13).<ref>Voss (2006, p.&nbsp;138)</ref> By its linear nature, the Long Count was capable of being extended to refer to any date far into the past or future. This calendar involved the use of a [[positional notation]] system, in which each position signified an increasing [[Multiple (mathematics)|multiple]] of the number of days. The [[Maya numerals|Maya numeral system]] was essentially [[vigesimal]] (i.e., [[numeral system|base]]-20) and each unit of a given position represented 20 times the unit of the position which preceded it. An important exception was made for the second-order place value, which instead represented 18 × 20, or 360 days, more closely approximating the solar year than would 20 × 20 = 400 days. The cycles of the Long Count are independent of the solar year.

Many Maya Long Count inscriptions contain a [[#Supplementary Series|supplementary series]], which provides information on the [[lunar phase]], number of the current [[New moon|lunation]] in a series of six and which of the nine [[Lords of the Night]] rules.

Less-prevalent or poorly understood cycles, combinations and calendar progressions were also tracked. An ''819-day Count'' is attested in a few inscriptions. Repeating sets of 9 days (see below "Nine lords of the night")<ref>See separate brief Wikipedia article [[Lords of the Night]]</ref> associated with different groups of [[Maya mythology|deities]], animals and other significant concepts are also known. <!--Because of the unknown elements of "819-day Count" and its assumed intervals, this needs citations.-->