Blinking snake

The Correlation of the Mayan and Julian/Gregorian Calendars

by Linda Schele
(with minor editing by Ivan Van Laningham)

The following was sent to Milo Gardner on May 6 1994 as e-mail because I had not yet figured out how to reply to AZTLAN. For those who are interested, here is the reply to his question about the correlation and Floyd Lounsbury’s number.

First of all, you must understand I am not a number person. I am a good friend of Floyd’s and have watched him argue the correlation problem with David Kelley for 25 years. Floyd did not send me a preprint copy of his correlation paper because he knows I am not a number person, and the “Sky in Mayan Literature” was not available until very late 1992, when the manuscript for “Maya Cosmos” was going through its final editing process before going to Morrow for production. If you have published books, you know that any changes made after the stage of copy editing causes apoplexy in harried editors.

But I probably would not have cited Floyd’s article anyway, because I was not attempting to make an argument about the correlation—only stating that David Freidel and I would be using the 285 correlation instead of the 283. Moreover, “Maya Cosmos” was written for the general public first and professionals secondarily. In my experience, there are people who think in numbers and who love them. For this kind of mentality (which Floyd and Dave Kelley have and I patently do NOT—this is a big joke between us), the Dresdon Codex, the eclipse tables, and other such things are the best way of entering Maya studies. But for most people, the numbers are opaque and mind numbing. For instance, I took Floyd’s seminar on glyphs in 1974-1975. He taught us the Venus tables and the eclipse tables. I was supposed to have learned from the master. All of his lessons fell on deaf ears. I could not reproduce any of it and understood less. In the workshops here I describe the experience as “it all made sense when I heard it, but when I walked out the door, it dribbled out of my left ear.” It’s the “left ear” syndrome.

I finally learned how Venus works by taking EZCosmos 3 and adding the appropriate intervals over hundreds of years and watching what happened. I learned it through the geometry of the sky rather than the numbers. Same thing for the eclipse tables. The rows of number that Floyd put in this Encyclopedia of Science article were just that—rows of numbers. I learned how the eclipse table worked by using the eclipse finder in EZCosmos 4 to construct my own table for the Maya last summer in our Antigua workshop. This semester I did the same sort of thing in our Dresden seminar by using EZC 4’s eclipse finder to check the Dresden eclipse table against the real world using all of its eligible base dates. After that, Floyd’s numbers made sense to me.

At a conference here in Austin last November, Dennis Tedlock argued with me about this. He argued that there are other hierophanies just as good for the Venus pages as the ones Floyd Lounsbury presented. Dennis assumed as many others have, that I prefer the 285 for the same reasons as Floyd does. But you have to understand that I have never fully understood Floyd’s reasons.

I have been convinced that the 584283-5 correlation was the correct family because of the astronomical alignments we kept finding, but as Dave Kelley says, the astronomy falls into regular periodicities that can be used to support many different correlations—as they have been for a hundred years. Dave doesn’t even believe that the 584283 family is correct; for me the problem has been to chose between the 283 or 285. In general, the astronomy does not help because almost all of the known events have a one or two day or greater fudge factor in them. You cannot use them to select between the one or the other.

Dave Kelley gave me what I consider to be the critical clue twenty years ago. The eclipse table of the Dresden Codex lists a 13 Ahaw that falls on 13 Ahaw 18 Kumk’u if the initial 12 Lamat base date is used. In the Dresden sequence, this marks as a new moon with an eclipse station. More over, the same augury that appears in the Dresden Codex also occurs on Quirigua E east side as the age of the moon in the lunar series. I take this to identify both in the retrospective chronology of the Dresden and in the real time chronology of the Classic period as an eclipse station and a new moon.

584285 answers this limitation. It was a new moon and an eclipse eliglible date. There was no visible eclipse on that day at Quirigua, although there was one of about 20% at Tikal. However, there was a 94% umbral lunar eclipse on Feburary 4, 771 fifteen days after That alone would have confirmed the correctness of the identification. was a lunar eclipse and the next day is marked at Copan as the heliacal rising of the Eveningstar. 584283 puts on Jan. 18, 771, which was not an eclipse date. Moreover, as I found out last summer in constructing a modern eclipse table with the Maya, 583283 does not place July 11, 1991 on an eclipse station and 584285 does. This was the date of the total eclipse over Guatemala City.

Finally, I have not read the two other sources you cite. However, I am confused by your reference to a fourth calendar. Do you mean fourth codex? I do not accept that there were many different calendars running at the same time as some people have proposed. We have a difference in the year bearers between the Dresden, the Yucatecan, and the highland calendars, that resulted in a slippage of the interlocking of the tzolkin and haab—that is, on which set of days 1 Pop would fall. Justeson has suggested a slip of one month in the epi-Olmec calendar, but so far I see no evidence that they are counting from different bases.


  1. Kelley, David H., “The Maya Calendar Correlation Problem,” in Kolata, Alan L., and Richard M. Leventhal, eds., Civilization in the Ancient Americas, University of New Mexico, Albuquerque, 1983, p. 157.
  2. Kelley, David H., “Eurasian Evidence and the Mayan Calendar Correlation Problem,” in Hammond, Norman, ed., Mesoamerican Archaeology: New Approaches: Proceedings of a Symposium on Mesoamerican Archaeology Held by the University of Cambridge Centre of Latin American Studies, University of Texas Press, Austin, 1974.
  3. Lounsbury, F. G., “The Base of the Venus Table of the Dresden Codex, and Its Significance for the Calendar-Correlation Problem,” Maya File 123, Maya File 316h.
  4. Lounsbury, Floyd G., “Maya Numeration, Computation, and Calendrical Astronomy,” in Dictionary of Scientific Biography, ed., Charles Coulston Gillespie, Vol. 15, Supplement 1 (1978), Scribners, New York, 1978 (Maya File 316e). (Note: This is the reference Linda means when she refers to the “Encyclopedia of Science” article.)
  5. Lounsbury, Floyd G., “A Derivation of the Mayan-to-Julian Calendar Correlation from the Dresden Codex Venus Chronology,” in Aveni, Anthony F., ed., The Sky in Mayan Literature, Oxford University Press, Oxford, 1992, p. 184. (Maya File 316g)
  6. Lounsbury, Floyd G., “A Solution for the Number of the Mayan Venus Table,” in Aveni, Anthony F., ed., The Sky in Mayan Literature, Oxford University Press, p. 207. (Maya File 316f)
  7. Owen, Nancy Kelly, “The Use of Eclipse Data to Determine the Maya Correlation Number,” in Aveni, Anthony F., ed., Archaeoastronomy in Pre-Columbian America, University of Texas Press, Austin, 1975, p. 237.
  8. Tedlock, Dennis, “Myth, Math, and the Problem of Correlation in Mayan Books,” in Aveni, Anthony F., ed., The Sky in Mayan Literature, Oxford University Press, Oxford, 1992, p. 247.
  9. Thompson, J. Eric, “Maya Chronology: The Correlation Question,” in Contributions to American Archaeology, Volume III, Nos. 13 to 19, Carnegie Institution of Washington, No. 14, 1937, pp. 51-104.

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