Other than the Calendar Round and Long Count, the ancient Maya used other systems for guiding their culture, which archaeologists understand to varying degrees. These “calendars” include the cycle of Venus, the Lords of the Night sequence, the 819-day count, the cycle of the moon and possibly the cycle of Mars.
Ancient Maya astronomers appear to have calculated Venus’s cycle this way: it rose as the Morning Star for 236 days, disappeared after this for 90 days, rose as the Evening Star for 250 days and disappeared for 8 days before becoming the Morning Star again. This makes a total of 576 days.
However the way the ancient Maya calculated Venus’s cycle does not accurately reflect what happens. Venus actually goes through a cycle that varies from 580, 587, 583, 583 and 587 days for an average of 583.92 days per cycle. It is the Morning Star for around 240 days, disappears for about 90 days, is the Evening Star for around 240 days, disappears again for 14 days and finally is the Morning Star again.
The ancient Maya kept track of the moon, calculating lunar months. As the lunar month equals about 29.53059 days, the ancient Maya tried to figure out a way to calculate the lunar month in terms of whole numbers and succeeded. They found that 4,400 days is very close to 149 lunar months (4,440/149 = about 29.53020). Seven pages of the Dresden Codex talk about lunar months. You can see records of the moon in inscriptions of the Long Count.
K’awiil 819-Day Cycle
Mayan gods could have multiple forms or “aspects”. K’awiil (also known as God K to archaeologists) is a god believed to be a lightning god and possibly a patron god of kings. It is also understood that he had four aspects, each connected to a color and direction: red is paired with west, white with north, black with west and yellow with south.
The 819-day cycle -- which may have begun at Palenque -- associated with these four aspects. When expressed, the 819-day count goes like this: a glyph could be a verb comes first, then a number in the 819-day cycle, followed by a reference to K’awiil, then a cardinal direction and then a color. The purpose of this “calendar” is not fully understood, It is possible that it was used for rituals.
Nine Lords of the Night
This “calendar” is understood to be nine-day cycle of the Nine Lords of the Night -- the gods of Xibalba, the Maya underworld. Each of the nine gods took his turn being connected to a day. Though not entirely clear, in Long Count inscriptions there are two glyphs that they think are connected to the sequence of the Lords of the Night. The Lords of the Night glyphs are numbered G1 through G9.
In the Dresden Codex there is a table that talks about numbers that are multiples of 78. Mars has a synodical period of approximately 780 days, so it is possible that the ancient Maya kept track of Mars cycle in the sky.
“The Ancient Maya”; Robert J. Sharer, Loa P. Traxler; 2006
“Understanding Maya Inscriptions”; John Ferguson Harris, Stephen K. Stearns; 1997
"Handbook to Life in the Ancient Maya World"; Lynn V. Foster, Peter Mathews; 2005
"Yaxchilan: The Design of a Ceremonial City";Caroline Elaine Tate; 1992