Astronomical Checks on the Correlation.
The first astronomical checks which develop from the correlation explained above are dates which reach the equinoxes, solstices, etc., further marked by special hieroglyphs which are to be explained as ideographs of these stations in the natural year. For instance the most emphatic date in the three famous temples of the Sun, the Cross, and the Foliated Cross at Palenque is one written 9.12.18.5.16, 2 Cib 14 Mol, September 23, 430 A. D., which coincides with the autumnal equinox. In connection with this repeated date we find two glyphs both of which are admirable ideographs of the equinox. One is Ahau, a face explained as that of the Lord of Day, but here half covered with starry eyes, and the other is the Kin or sun symbol, half darkened with cross-hatching. At Comitan a round number date exactly coinciding with the equinox has a variant of this second ideograph.
Other strong proofs concern Venus and the Moon. Hieroglyphs of these heavenly bodies are found in combination with dates and these later actually reach significant phases of the planets in question. For Venus the phase chosen is commonly the first appearance as Morningstar four days after inferior conjunction, or what is known as the heliacal rising. Records of the Moon are prominent when a new or full phase coincides with a round number in the day count.