This site: http://www.themystica.com/mystica/articles/d/discovery_of_the_sequani_calendar.html
claims the discovery of a “Sequanic Calendar”, deriving from something found in the former lands of the now-extinct Sequani Celtic tribe. Purportedly, it correlates the solar and lunar calendars and pagan and Christian holidays.
It seems like baloney to me, but perhaps I am too skeptical. Or not. Enlighten me.
Well, the home page would seem to indicate a need for skepticism: It says that it is: An on-line encyclopedia of the occult, mysticism, magic, paranormal and more…
Peter Meyer is an acknowledged calendrical expert:
http://hermetic.magnet.ch/cal_stud.htm
His “links” page provides several links concerning the Coligny Calender and several other historical calendars:
http://serendipity.magnet.ch/hermetic/cal_stud/cal_lynx.htm#coligny
One of those links, which seems to be non-occult and reasonably informative: