The validity or invalidity of calculation coefficient that serves to transfer the Mayan dates to our system of dating could be verified by those Mayan dates, which are evidently concerning some well known astronomical phenomena. As the best for that purpose we can employ two known dates from the Dresden Codex.

First of them, on the page 24 ( Knorozov ), is a Mayan date (in decadical form) 1,364,360 days, to which are added the important points of visibility of the planet Venus (J.E.Teeple 1926). According to the mentioned Mayan date and Mayan calculation, the Venus should have been visible for 4 7 days after its lower conjugation as a morning star before the sunrise. Wen using the Bohm MD/JD calculation coefficient (622,261 days), the Mayan date 1,364,360 is converted into the 27th January 727 the day, when the Venus was 8 days after its conjugation, which happened on the 19th January 727. It really shone on the sky as a morning star shortly before the sunrise.

When using the G-M-T calculation coefficient (584,284 days), the Mayan date 1,364,360 is converted into the 5th February 623. In this time, The Venus was situated 15 days before the lower conjugation. The Mayas would not have done such a mistake (20 days) in their observation of the planet Venus.

We have determined, using the Bohm MD/JD Correlation (622,261 days) the second Mayan date 1,412,848 days on the 31st page of the Dresden Codex, which is essential for calculating the period of eclipses (M.Meinshausen 1913, C.E.Guthe 1921, H.Spinden 1930), as the date 29th October 859. This is the real date of a sun eclipse visible in the whole Mayan region. By calculating with the help of the G-M-T correlation coefficient (584,284 days) we get the 7th November 755, when there was no visible solar eclipse.

From the upper mentioned analysis is apparent, that the until today used Goodman-Martinez-Thompson correlation coefficient is not right. Even if we allowed, that the Mayan astronomists could have made a mistake of several days during the planet synodic circulation calculation, they could not have made a mistake greater than a single day calculating the moon and the sun eclipses, because these phenomena are temporally very tightly limited and the calculated eclipses would not take place. The mentioned Mayan date of 1,412,858 days from the Dresden Codex is from that point of view very important for the eclipse period calculation.

The G-M-T Correlation has been shown incorrect also by the historical connections and the continuity of the Mayan calendar in the later Aztec dating system. But these are the topics of our next published studies.