Update:

https://docs.google.com/spreadsheets/d/1Tv9K1DNFQ1eIEa_WnPqQg_HgLsZYdX1J4gXlDaNtiPo/edit#gid=0
First 2 columns are Easter and Pentecost as celebrated by Roman, Arian, and Orthodox Christians.
Second 2 columns are Easter and Pentecost as celebrated by British Christians.

Edit: It occurs to me that I have no idea what Easter practices Arian Christians followed. I was just blithely listed the 'not-British' versions of Christianity from pendragon.
-------------------

The dates for Easter and Pentecost by year.

More detail than you, I, or anyone needs.

----An important note to start----

This chart is mostly useless for Pendragon because these are the dates that would be celebrated by ROMAN christians.

KAP 5.1, page 142:
"Most importantly, there is a dispute between the British and Roman Churches as to the date for Easter. The rationales behind this dispute are far too esoteric to go into here, but since Easter is the most important holy day for both churches, this dispute is prominent in the friction."

Esoteric is a good word for it. Basically the date for Easter (and therefore Pentecost) will be different for courts that use the British christian method of calculating Easter. Easter and Pentecost will always fall on a Sunday regardless - so at least you know it will be some multiple of 7 days before or after the date given on this chart.

----Public service announcement over----

I was trying to figure out what the yearly schedule is like, which of course includes the Pentecost court. So I sez, "When is Pentecost anyway?" Many articles, google searches, head scratching, quite a few hours later...

https://docs.google.com/spreadsheets/d/1HZDz8e84dRCcbHbosTSRwfT7Yc7EBJJuR4qpeCcHN0s/edit?usp=sharing

This chart is based on the information on this link:

http://christianity.about.com/gi/o.htm?zi=1/XJ&zTi=1&sdn=christianity&cdn=religion&tm=57&f=20& tt=65&bt=5&bts=4&zu=http%3A//www.assa.org.au/edm.html

I invite anyone who can follow the formulation to check my math. I'm particular insecure about math I created to "add" days and dates.
e.g. April 15 + 25 days = May 10

I couldn't use the built-in date functions for google docs because they don't work for first millennia dates.

I couldn't use the built-in date functions for google docs because they don't work for first millennia dates.


Slackers! And yet they have time to develop cars that drive themselves!


T.

On a quick glance, I think you took into account the differing lengths of the months (March 31, April 30 and May 31).

I admit that while I knew that the Easter date fluctuates quite a lot with the full moon, I didn't actually realize that it can be almost a full month if you get 'lucky/unlucky'. I usually just fudged it anyway: "Easter is in the start of April and Pentecost is 50 days after that, which would make it late May, just before June." Works well enough for us. :) But yeah, might use this to mess with the players' heads a bit. :P So thanks!

This is very cool, Sir Knighty. I will definitely use this.

One thins that gets glossed over a bunch is the the New Year was not Jan. 1 in the Middle Ages. See the last paragraph in this short article to get the scoop:

http://andreacefalo.com/2013/01/01/5-facts-about-medieval-new-years/


T.

Ah, but we are playing in the Dark Ages, surely? :)

The second paragraph of your link, Taliesin, states:
"5. Julius Caesar declared January 1st as the New Year in 45 BC, starting the tradition. Caesar chose the date because the month of January is named for the Roman God Janus, a two-faced God who looks to the future and past. The Council of Tours abolished January 1st as the beginning of the New Year in 567."

Since most of Pendragon is pre-567 AD, using January 1st is perfectly alright. :)

Good point. I'll admit to a little bit of confusion on the whole date-thing. My understanding is the Uther Period conforms with the 10th century when it comes to technological and societal development . Yet clearly there are real-world historical events that correspond to the dates in the GPC. S0 — are we playing in the 5th cen or the 10th? Then you have the whole compressing-all-of-the-Medieval-period-into-80-years, or whatever. This has always been a little vexing to me. I guess the GM can decide on the date New Year's falls on. I was just pointing it out for those who may not have encountered that bit of trivia before. If you want to give an even more "alien" feel to your campaign, you can always make New Year's Day fall on March 25th...


Best,


T.

Want to start a new thread to discuss the anachronisms inherent in Pendragon, Taliesin? I will restrain my urge to contribute to the thread drift here. :)

I found a little bit information about the subject of calenders and years and news year while I researching calender stuff.

None these links are anything you couldn't find with a quick google search, none the less...

http://www.medievalgenealogy.org.uk/guide/chron.shtml
Most of the information in my post comes from here, you're probably better off reading it than reading my post.

http://www.getty.edu/art/gettyguide/videoDetails?cat=3&segid=2021
A short video that explains the church calender. And gives some information about how people would refer to dates if they were using such a calender. Rather than "11th of June" they would say "4 days before the ides of June"

The start of the year moved around a bit. Julius Caeser declared it the 1st of January (as mentioned). In 567 the catholic church decided that new years was too pagan of thing to be celebrating and repealed that.

I guess I should also point out that the AD system of numbering years was invented in AD 525, but it wasn't widely adopted for many centuries. At the time roman years were labeled based on the whoever was consul at the time. And since there were 2 consuls, it was somewhat arbitrary which name was used. Also consuls often served several non-contiguous terms. And there aren't that many different names a roman could have... basically it sounds like a terrible system.

"In the 4th year in the consulship of Steve..." "When was he consul again? Was that before or after Bob..." "He served at the same time as Bob." "Oh, so that's 5th year of Bob..." "What? No no. Bob wasn't serving at that point, Joe was." "Joe? That was a decade ago!" "Yeah." "Wait... you mean Steve the Elder?" "Of course Steve the Elder!"

Those 2 details may well segue into the concept of regnal years. This seems to have been the dominant method under Norman rule. When speaking terms of regnal years it was common to give the day relative to the next feast or holiday.

"The thursday before the feast of St. Whosit, in the first year of King Athur's rule"

A new regnal year begins on the date of either the kings accession or coronation. You can read wikipedia for the definition of accession, I'm not totally clear on it. The point that these are two different dates. To make it potentially extra confusing - if the coronation occurred on a movable feast day (like easter or pentecost) then the new year would begin on that feast day.

"Who's the consul now?" "Yes." "Yes is the consul?" "No, who is." "That's what I'm asking!"

Nah, thanks, Morien. I just intended the New Year's thing as a quick inside. Don't think there much to say that's not already been said.


T.

OK, I am not sure I'd ever use this, but I think it is really, really neat.
Can I post it on my KAP website?

Will you figure out the dates for the British Church too, for me (and the nerd world!)?
For them Easter was on the 3rd day following the first full moon of spring
Same moon phase, but just not necessarily on a Sunday

And so what is the date of Spring for these calculations?

OK, I am not sure I'd ever use this, but I think it is really, really neat.


I don't think I will either!



Can I post it on my KAP website?


Sure.



And so what is the date of Spring for these calculations?


The vernal equinox varies a bit each year, so the church used the static date of March 20th as an approximation. (also the Julian calender drifts off from the actual solar year by 3/4 of a day every 100 years.)

First full moon is even trickier - the date of the first full moon depends on your time zone. The church didn't want Christians in the middle east celebrating Easter a week after the ones in Rome... they wanted everyone to celebrate Easter on the same calender date each year. So instead they used the Hebrew calender to estimate the date of the full moon by fixing it to the 14th day of Nisan.

So basically the non-British method is to calculate the first fake full moon after the fake vernal equinox. To be fair, they have reasons for doing it this way. For one they actually know when Easter will be ahead of time - so if they want to plan a big celebration for the Pope's 10th anniversary or whatever, they can.


Will you figure out the dates for the British Church too, for me (and the nerd world!)?

I've seen a few different explanations of the British method. There was apparently an 84 year cycle of some kind with some associated tables. They haven't survived though.

It's also been suggested that they used 15th day of Nisan and the 21st of March for their approximation.


For them Easter was on the 3rd day following the first full moon of spring
Same moon phase, but just not necessarily on a Sunday

Actual full moon?

I'd have to know the actual dates for the full moon...

http://www.timeanddate.com/calendar/moonphases.html?year=485&n=136

Calculating the actual date of Easter seems doable.

When you say 'start of spring', do mean the vernal equinox? Just want to be sure, as there are other methods of determining the start of spring. In some places the vernal equinox marks the mid-point of spring rather than the start. The Irish traditionally use the fixed date of Feb 1. (according to Wikipedia)

If it is the vernal equinox...

http://www.timeanddate.com/calendar/seasons.html?year=450&n=136

I think the hardest part of calculating the date of astronomical Easter (since someone already did the actual astronomy for me) is typing in all the dates manually. I should send a strongly worded email to google and the OpenOffice foundation. (though I think in both cases they're just trying to match previously established standards)

I'm reminded of the story in Bede about how the confusion over how to calculate Easter had grown to such an extent that King Oswy of Northumbria was celebrating Easter with his nobles while the Queen and her household were still observing Lent. (At least until Oswy presided over the Synod of Whitby to settle the matter permanently.)

https://docs.google.com/spreadsheets/d/1eStNg4Hr1ItChuNSxtuwJOnCu_SvuO-ijEGHWG9GjNw/edit?usp=sharing

The following assumptions are used:

Beginning of spring = vernal equinox
Start of the day is determined in the roman manner (midnight)
"on the 3rd day after" = three days later

I have a feeling the second and third assumption are incorrect

And here is both on one chart (with none of the horrible hack-y calculations visible)
https://docs.google.com/spreadsheets/d/1Tv9K1DNFQ1eIEa_WnPqQg_HgLsZYdX1J4gXlDaNtiPo/edit?usp=sharing

You rock man!



The following assumptions are used:

Beginning of spring = vernal equinox
Start of the day is determined in the roman manner (midnight)
"on the 3rd day after" = three days later

I have a feeling the second and third assumption are incorrect

Close enough for me.
I got the +3 days from one of the references you gave earlier


And here is both on one chart (with none of the horrible hack-y calculations visible)
https://docs.google.com/spreadsheets/d/1Tv9K1DNFQ1eIEa_WnPqQg_HgLsZYdX1J4gXlDaNtiPo/edit?usp=sharing

What are v1 and v2 differences based on?
I just want to put one definitive list on site.

This is pretty cool
Even though I still don't see much use in play :)

I'm not confident enough to call it definitive, but you are still of course welcome to put them up on the site.

V1 is based on astronomical data from that timeanddate.com website.

The three days thing reminded me that Jews start the day at sunset rather than midnight. (if you go back far enough they use sunrise as the start of the day, but I'm not sure how far back that was)

V2 is if you took the paschal full moon from the non-British method added three days. It's basically the statement "Same moon phase, but just not necessarily on a Sunday" taken too literally. I might just go ahead and remove it.


I got the +3 days from one of the references you gave earlier

Do you happen to recall which link it was? The pedant in me is curious to see the exact wording.

There was a quote from a British emissary to Rome, arguing in favor of the British method. The jist of it was that the British celebrate Easter with 'light of the full moon shining above them'. So actual full moon + 3 days at least follows the spirit of what the British Christians were after.

I can't remember where I saw that the quote though.

It was the article
http://www.historicism.org/Documents/Jrnl/PelagiusPatrick.pdf
Page 15

and the quote:
The champions of Rome sought the real decision of this battle [between Irish and Roman
Christianity] in another area: they reproached the Irish abbots because their followers did not,
like Celtic Christians in France and north-west Spain, celebrate Easter on the Sunday following
the first full moon of spring but, in accordance with Greek custom, only on the third day after this
phase

It might be useful to find out what the Eastern churches have to say, since the British seems to be closely related to them on this matter.

Also, the Celtic British started a 24-hour period with nightfall.

Ah ok! The Greek custom referred to their is way that the Greeks were handing Easter before the council of Nicea in AD 325.

Eastern and the Roman churches calculated Easter in the same way at this point in history. (They don't diverge again until 1582 when the Orthodox church did not to adopt the Gregorian reform of the Julian calender)

When I say the midnight is the roman method, I meant that is the normal roman method of tracking the start of a new day. (the same one we use) For the purposes of determining the date of Easter sunset is used.

Three days after the start of passover (the first full moon of spring), would be (I believe) what I called "v2" before. I have relabeled the comparison chart.
https://docs.google.com/spreadsheets/d/1Tv9K1DNFQ1eIEa_WnPqQg_HgLsZYdX1J4gXlDaNtiPo/edit#gid=0

Pedantically I don't think this method is historically accurate, but it fits with the British as Pelagianists setting. Also the exact historical method is unrecoverable - we just don't have the 84 year cycle charts.

I promise you I don't intentionally waste my own time or discover information when dramatically appropriate. I did a lot google searching before I started trying to work it out these various speculative british easters. Apparently I just hadn't used the right magic words.

The "lost" 84 cycle was recovered in 1987, not only that the historians responsible have already calculated the dates for easter for 438 to 521.

https://www.cs.tcd.ie/misc/kronos/
http://www.mgh-bibliothek.de/dokumente/a/a149668.pdf

So far I've just copied down the chart that the historians with doctorates made.
https://docs.google.com/spreadsheets/d/17sTAxkar-18Uvta8lXtxL6I67ZaJwa3W5qkqcehzLsM/edit?usp=sharing

I don't actually know what this chart means yet, as I haven't finished reading the paper. But you are free to admire it.

http://eprints.nuim.ie/1331/1/PHD_Thesis_corrected_copy_1st_July_08.pdf

Starting at Page 281 in the index of this thesis there is a chart for British Easter that extends over the whole of the period of the GPC.

(The paschal date on the chart)

Barring fence posting errors on the Pentecost calculation or transcription errors on my part.

https://docs.google.com/spreadsheets/d/1Tv9K1DNFQ1eIEa_WnPqQg_HgLsZYdX1J4gXlDaNtiPo/edit#gid=0

Interestingly, it matches up most years.

So:
Roman/Orthodox Easter
The date of Easter as calculated by most churches in the period, as laid down by the council of Nicaea in AD 325.

British/Irish Easter
Date as calculated from the reconstructed 84 year cycle used by Irish churches (and in many areas influenced by Irish missionaries).

"Lunar" Easter
My attempt to get the date of Easter based on the scientifically accurate vernal equinox and lunar phase cycle. Abandoned after I realized I couldn't precisely determine the time of sunset.

QD+3
The date of british Easter suggested by the Frank W. Hardy paper.
QD in this case stands for Quartodecimanism, which was the practice in some regions before the council of Nicea to celebrate Easter on Nisan 14, at the start of Jewish passover. Many roman sources seemed to believe that Irish Christians were following the practice. They probably didn't really understand the actual practices of the Irish Christians and were trying to fit it into their understanding of earlier controversies regarding the date of Easter.

You Rock Sir Knightly

Will you please contact me off line? You can find my email in many places.

Thank you

--Greg

You Rock Sir Knightly

Will you please contact me off line? You can find my email in many places.

Thank you

--Greg


You are very kind. I feel embarrassed at my haphazard and over-labored way of finding the information.

Email incoming.