According to Schele and Freidel, the lower masks represent the sun at each horizon; the upper masks symbolize Venus as morning and evening star.
In the Classical period (200-900 AD), Venus and the sun were identified with Hun Ahaw and Yax Balam, the "hero twins" who defeated the Lords of the Underworld, making creation of the present world possible.
At this time, Venus lies between the earth and sun.
The midpoint of this period of invisibility is the moment of superior conjunction.
The left hand sides of pages 46-50 (according to the conventional page numbering) contain a table of dates of the rising and setting of Venus as morning and evening star.
On each of these pages, the last station of Venus listed is heliacal rise.
On the right hand side of each page, deities and auguries associated with heliacal rise are illustrated.
A huge pair of jaguar masks decorated a temple facade at Cerros in about 50 BC.It rises earlier, and thus rides higher in the sky at sunrise until it reaches maximum western elongation, about half way through its apparition as morning star.Thereafter, it rises progressively closer to sunrise, finally rising after the sun so that it is lost from sight.It re-emerges from the sun's glare when it rises at sunset (cosmic rise).It then rises progressively later as evening star until it reaches maximum eastern elongation.