The zero of the Mayan day count, reached by subtracting 12.9.17.9.4 or 1,799,104 days from the position declared above, is shown to be October 14, 3373 B. C. in the backward projection of the Gregorian calendar. The Gregorian readings are preferable to the Julian because they preserve the actual times in the tropical year, but it is sometimes useful to use the days of the Julian Period which can always be found by adding 489384 to the Mayan number.
Now Mayan history does not reach back to the zero date which must be regarded as a theoretical beginning or Mundane Era. The earliest object with a contemporary date is the Tuxtla Statuette with May 16, 98 B. C. It appears, however, that the really historic beginning of the day count was 7.0.0.0.0, 10 Ahau 18 Zac, August 6, 613 B. C. The calendar of months was probably inaugurated in 580 B. C. when 0 Pop, New Year’s day, coincided with the winter solstice. A third era, 9.0.0.0.0, 8 Ahau 13 Ceh, February 10, 176 A. D., is the one used in the Mayan chronicles.
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.
Astronomical Observatories.
One of the most interesting pieces of evidence in support of the correlation explained above has to do with a giant sun dial at Copan. Two stelæ stand on opposite sides of the valley establishing a line which runs about 9 degrees north of west. When observation is made from the eastern marker the sun sets behind the western stone two times during the course of a year, once shortly after the vernal equinox and once shortly before the autumnal equinox. Now the Mayan chronicles state that the calendarial New Year was “counted in order” during a certain Katun 13 Ahau which extended from 491 A. D. to 511 A. D. Altar U at Copan was observed to record two New Year’s dates equaling April 9 in conjunction with another date, equaling September 2, 503 A. D., and falling in the required interval covered by Katun 13 Ahau. These dates were such as might be reached by just such a base line as exists at Copan and it was first believed that they were exactly reached by it. Careful reconsideration of the evidence in the inscriptions and a re-survey of the line of sight led to the interesting conclusion that the sun dial of Copan was originally set up in 392 A. D. to give sunset coincidences on April 5 and September 6. About 490 A. D. the stones were re-adjusted to give the April 9 and September 2 which are recorded on Altar U and still later a third and present arrangement was effected giving April 12 and August 30. Each pair of dates is “reciprocal” in the sense that one member marks the same interval after the Spring equinox that the other does before the Fall equinox. The shifting seems to have been decided upon by astronomical congresses, and the purpose was to fix propitious times of planting the crops.
Fig. 49. Diagram of the Astronomical Base Line at Copan giving readings at April 9 and September 2. Slight shifts were made in this line: at an early time it was arranged to read April 5 and September 6 and at a later time April 12 and August 30.
Other Mayan observatories at Uaxactun and Chichen Itza have lines of sight which mark exactly the positions of the sun (the summer solstice, etc.), and all in all the evidence deduced from these observatories is in complete agreement with the correlation of the Mayan and Christian time counts originally effected on the evidence in sixteenth century documents.