Dreamspell & Lunar Calendar
It is my interpretation of the Dreamspell 13-Moon Calendar (for more info see here: http://www.lawoftime.org).
Each day on the Dreamspell calendar has a "seal" associated with it. There are 20 seals which repeat from the first to the last for 260 days. The 13 times the seals repeat are linked to 13 moons which repeat in a 28 day cycle. The calendar recognizes 364 days to make up a year. The year starts on July 26th and ends on July 24th. July 25th is the 365th day and it is considered a "day out of time". The daily seal algorithm put out by the Foundation for the Law of Time uses look up tables tied to years and months with an epoch of 1858. It is not clear where they got these numbers from. But using the tables I was able to derive an algorithm to calculate any seal starting from the epoch date.
The lunar phases are calculated using a public domain program I found here:
There are several of these algorithms floating around by various authors. I found a good resource for astronomy algorithms at Sky and Telescope magazine:
it is surprising how arcane some of these algorithms are. Very little explanation about how they are derived is available anywhere.