The epoch for the calendar is the year 444 C.E. and the era is called A.S.E. (Anglo-Saxon Era). The years are therefore approximately 444 years behind those of the Gregorian calendar.
Days of the week
The days of the week were named after Norse deities, apart from Saturday, Sunday and Monday, and have the same origins as the names that are still used today. The Old English names for the days of the week were: Sunnandæg, Monandæg, Tiwesdæg, Wodnesdæg, Þunresdæg, Frigedæg, and Sæternesdæg.
The main festive days observed in the calendar are as follows, with typical equivalent dates in the Gregorian calendar:
- Yule, 30 Aergiuli - 1 Aeftergiuli (20th - 21st December)
- Winter Cross Quarter, 16 Solmonath (4th February)
- Ostara, 1 Eostremonath (21st March)
- Egg Moon (Movable - first full moon of spring)
- Spring Cross Quarter, 16 Thrimilchi (5th May)
- Litha, 31 Aerlitha - 1 Aefterlitha (21st - 22nd June)
- Summer Cross Quarter, 16 Weodmonath (6th August)
- Harvest Moon (Movable - last full moon of summer)
- Mabon/Harvest Home, 31 Halegmonath (21st September)
- Autumn Cross Quarter, 16 Blotmonath (6th November)
In popular parlance, the Harvest Moon is the full moon closest to the autumnal equinox, therefore it could occur in the last half of Holimonth or the first half of Winterfylleth. In more northern climes, however, harvest would tend to occur earlier than this, and this fits with it being the last full moon before the equinox in my calendar. This means that it will usually fall in the month of Holimonth, which interestingly enough, has the alternative name of "Harvestmonth" (Haerfestmonath).
More on leap years
The rule for leaps years is simple - if there are 366 days between one winter solstice and the next, then the year is a leap year. If we wish to autamte this for representation on a computer system, we must have some way of calculating when each winter solstice will occur in GMT. There are arithmetical formulae to work this out, but they are very complex. However, to reduce this complexity we can use a variable, or progressive, rule, rather than a fixed one. In the case of the south solstitial year, i.e. the year between two south solstices, this was relatively stable up to around 1500 CE, is currently getting shorter at a relatively high rate, and will stabilise again around 9000 CE. The rule employed therefore uses a linear approximation of the downward curve of the mean south solstitial year length during this period. It is not as simple as a fixed rule, but is simpler than the astronomical algorithm required to do the same thing.
The rule employed is called LASSY, which stands for Linear Approximation to the South Solstitial Year, and was devised by Dr. Irv Bromberg of the University of Toronto. Dr. Bromberg has devised several leap rules for use with experimental or notional calendars, in particular his Symmetry454 calendar, a calendar that uses a "leap week" instead of a leap day to keep it in synchronisation with the seasons. I have used his freely available algorithm to work out the start dates for my calendar for the A-S years 1 to 2556 (i.e. 444 to 3000 CE), with the offset parameter adjusted to -11.2, which appears to give the closest approximation to the date of the south solstice. I have checked as many of the resultant start dates against approximated solstice dates and so far only one year is out of sync, and on that occasion it is estimated that the solstice will occur one minute into the following day, so the rule is so far proving to be pretty accurate.
For more information on this subject, see the links below. I am extremely indebted to Dr. Bromberg for the information and the algorithms that he has made freely available on his web site, which have enabled me to employ this leap rule to my calendar. The graphs and diagrams are worth a look in order to gain an appreciation of how the orbital mechanics of the Earth work, and how these factors must be taken into account when devising a calendar.