Fun fact! The upcoming year requires intercalation, meaning we’ll have thirteen lunar months this time around to keep things synched with the solar cycle.
Some ancient Greek systems just repeated the final month*, while others gave the extra month its own name. The Bakcheion follows the latter custom, calling it Eriaphioteion after the Dionysian epiklesis Eriaphiotes meaning “insewn” or “stitched together,” since he was snatched from the smouldering wreckage of his mother Semele and placed in an artificial womb in his father Zeus’ thigh to finish gestating.
As a consequence of this most of our festivals (with the exception of Foundation Day, which is always on January 1st) will be about 3-4 weeks earlier than normal. Without this adjustment, however, we’d have seasonal creep resulting in Anthesteria being celebrated in autumn, or worse!
And note that this calendar, and its sequence of festivals, is just for the Bakcheion and those who wish to follow along – it is not in use by Hellenic polytheists or Dionysians in general, nor does it represent the “official” calendar of the Starry Bull tradition as a whole, although Starry Bull myth and cosmology definitely provides the backdrop for it. But different groups and streams of the tradition will have their own festival-cycles, calendars, etc. Anyone is welcome to use it, of course, it just has no binding authority outside the temple.
* A notable exception being the Rhodians who put their Embólimos or repeated month between the 6th and 7th.