Feastdays

a short computer program to display several movable feast days of any given year

John Kelleher

Feastdays calculates and displays several movable feast days of any given year, including Easter and the First Sunday of Advent.

It is tweaked for use particularly in the United States. If you run feastdays and enter the year 2008, the output looks like this (except for the bolded and starred entry on St. Joseph's day):

Movable Feasts for 2008 (United States)

Liturgical Year A. Advent I begins Year B. Christmas is on a Thursday.

*Nope. St. Joseph's day is celebrated on March 15 in 2008. See below.

According to the experts who designed the algorithms used here, the dates produced should be accurate from 1 AD on, though obviously the liturgical feasts may not have been relevant then. So, for example, you can find out on what day of the week Christmas was in 1776, if you're curious. Negative numbers (that is, BC dates) won't work, since they are obviously not relevant. Also note that since there is no year '0', entering 0 turns out to be a good choice for an exit code to close the program.

There is NO guarantee that the dates given by feastdays will be accurate. The dates given by feastdays are 'accurate' in the sense that they accurately follow the c. 2000 AD rules for determining feasts laid down by the bishops of the United States.

However, for bishops, who can make a Thursday into a Sunday (such as the Ascension, although in most U.S. dioceses, it's still Thursday) -- who can make any day of the week you want into a Sunday (such as the Epiphany) -- anything is possible.

For example: in 2008, March 19 (St. Joseph's day) falls during Holy Week. There was no current rule for this possibility. That 2008 would eventually happen apparently never occurred to anyone.

Feastdays, having no official rule to follow in 2008, simply gives the normal date for St. Joseph's day, March 19.

On the other hand, the 1960 Codex Rubricarum, perhaps more forward-looking than modern liturgists, did have such a rule: "proximum sequentem diem"; literally, "the next following day," which means the next day after March 19 that you could legally do it.

Sundays are out. Holy Week and Easter Week are obviously out. Also out, as it happens, is the Monday after the second Sunday of Easter (the day after Easter Week ends), which (by already established rule) in 2008 is given to the Solemnity of the Annunciation, because March 25 occurs during Easter Week.

So, even though no rule was currently in place, the logical place for St. Joseph's day in 2008, and the place it would have had under the old rubric, is "the next following day" after Monday, March 31; that is, Tuesday, April 1.

So what happened? In 2008, St. Joseph's day is celebrated on March 15.

A mere computer program can not cope with miraculous events. You should not expect it to.

In Windows, double-clicking on 'feastdays.exe' should open the program.

I wrote feastdays using the Linux operating system. I did not have a Mac available. I have included a compiled version of feastdays (called 'feastdays', NOT 'feastdays.exe') which MAY work in other Linux machines, and MIGHT even work in Intel-based Macs. No guarantees.

Feastdays is free, and has been made in the hopes that it will be useful, but there is no warranty of any kind for feastdays, in any of its versions. The included files called 'feastdays.c' and 'COPYING' have the details.

Mac users: you can only run feastdays from within the Terminal app; there is no GUI. Everybody else: there is no GUI for you, either. Feastdays is run purely from a terminal.

If my compiled version doesn't work, Mac (and Linux) users will need to compile feastdays themselves. They can do so by opening a terminal, changing to the directory where feastdays.c is, and typing this:

gcc -o feastdays feastdays.c

RIGHT-Click on the link and 'Save Link As' (Netscape/Mozilla/Firefox) or 'Save Target As' (Internet Explorer) to download:

feastdays.zip (50 KB)