Below is a PDF featuring my derivative of the Celtic Calendar found at Coligny in France in 1897. For a good article on the Coligny Calendar, see https://en.wikipedia.org/wiki/Coligny_calendar . And here’s a very interesting page on the Coligny Calendar from Caer Australis – https://caeraustralis.com.au/celtcalmain.htm .
The first page of the PDF explains the structure of the calendar as well as the calculations and modifications involved in it. I have used Celtic terms for “day”, “month” and “year”. For the 5-year cycle, I have opted for a (possible) Celtic cilcon based on Welsh cylch and Breton kelc’h. For the 30-year cycle, I have used saitlon (Welsh hoedl and Breton hoal), the Celtic equivalent of Latin saeculum.
I have not taken most of the various notations on the Coligny Calendar into account, including the reference to the TRINOVXSAMO (“Triply Most-High” – see https://vellaunos.ca/2022/01/24/samain-and-samonios/ ) on the seventeenth day of Samonios. I have also disregarded other features of the Coligny Calendar – for example, I have made the regular months alternate regularly between 29-day and 30-day lengths.
I have made the months start (approximately) on the day of the new moon, meaning that the day of the full moon would be (approximately) at mid-month. I would also suggest that the days of this Celtic calendar be considered to start at sunset on the previous day of the Gregorian calendar (it was apparently customary among the Celts to consider sunset to be the end of a day and the beginning of the next day).
The solstices and equinoxes are indicated on the calendar, as well as the midpoints between these. These latter are given the reconstructed proto-Celtic forms of the names of the Irish festivals that fell on them. Note that Lugunats on the eleventh day of Riuros is short for Lugunatsaton. Note also that the name Samanis on the thirteenth day of Cutios is the true original form of Irish Samhain (see https://vellaunos.ca/2022/01/24/samain-and-samonios/ ).
I have taken the liberty of dividing the half-months into two weeks. In a half-month with 15 days, the second week has 8 days rather than 7. I have also taken the liberty of assigning names of Celtic Gods and Goddesses to the days of the week, these appearing in the genitive case (e.g. (Diion) Belinî = (Day) of Belinos).
The months included in the PDF cover the period from April 1st to November 22, 2022. The first month in the PDF (Cantlos) is the last month of a previous saitlon (30-year period). The second month (an intercalary month called Cuimonios) is the first month in the current saitlon, which I’ve defined as the first saitlon.