It seems a shame that our calendar is in such a bad state that we have many alternatives and no obvious criteria for selecting between them.
The passage of time, and the endless astronomical cycles are a great gift to us…
I wonder if there would be any value in building a tool that can display the calendar based on the date of the heliacal rising at any location (south of about 70 degrees latitude)?
Well if you’ve got the time and the skills I’d say go for it!
I know I’ve mentioned these sites before, but thought it might be worth mentioning again.
I use a combination of the below links. The first one for the Heliacal rising date and the second for festival dates. But it is a pain to manually work out festival dates following the different Heliacal rising dates each year. Probably partly why I don’t celebrate many festivals.
https://www.ucl.ac.uk/museums-static/digitalegypt/ideology/festivaldates.html
Probably i will start with something that keys the festival dates off of the Gregorian calendar date of choice for Wep Ronpet.
After that, working out the heliacal rising accurately across time can be progressively refined. I already have code that works out the elevation above the horizon at a given time of day, longitude and latitude, which I can use to work out the date of the heliacal rising.
I’ll start on this during lunch. I should be able to make an all-in-one webpage anyone can save locally, and find some kind of free permanent hosting for it. Hopefully the first step will be done later today. 
EDIT: here is the WIP - it might update more slowly than I work in it however. so far its just a visual representation of a calendar that I can use to work out how to do the best job of this.
https://semiessessi.github.io/kemetic-calendar/
I’m wondering if I should start a thread so that everyone can have their input on this? Even if its slow to get feedback, I’d rather spend 15 years building something more useful and to an exceptionally high standard, than a month making something horrible that exacerbates, rather than eases, the practical problem here.
Obvious immediate questions are how to display names and numbers, which options people would like (e.g. Egyptological spelling vs. transliteration vs. hieroglyphs etc.)… and there is also the colour scheme and layout, which is decided purely by css so that it is easily replaced. I’ve taken my cues from a w3schools tutorial on making a calendar style layout using css in the hopes that will make it as accessible as possible.
Then there is how to display the current date, and perhaps festival information in some kind of sidebar etc?
EDIT 2: i will start a new thread about this…its now usable.
Approaching this problem has been insightful.
All the talk of chronologies based on computing heliacal risings is highly prone to error, and I can say this with confidence now.
I am not alone in this assessment. Although different papers on the subject contribute to the conversation without explicitly calling out the futility of the effort.
One of the interesting conclusions is about the so called arcus visionis of the famed astronomer Claudius Ptolemy. It is the altitude required for both the sun and a star on the date of heliacal rising, and he provides estimates for particular stars as observed from Alexandria, where the viewing conditions would have been markedly worse than at Memphis, Heliopolis or Thebes due to the humid atmosphere.
The latter paper explicitly mentions this by making comparisons with ancient Babylonian observations of Saturn, and considering modern models of atmospheric extinction.
That is not to say that the average of these observations in antiquity would not have resulted in a remarkably accurate and reliable calendar. However, dating efforts using software to predict positions as far back as 2000BC will suffer significant error, and even if these were removed (which seems unlikely), precision down to a specific date is practically impossible.
I have seen many publications citing software that does not include precession, changes in the obliquity of the ecliptic, polar wander, the true rotation rate of the earth, proper motion, and other significant factors in precisely pinning down the dates… yet make claims about specific dates.
Better models of Earth orientation at 1600BC and 2000BC than are typically used have 30m-1h of error, which is a wider error range than the more often mentioned ambiguity in observation site - usually between Heliopolis and Memphis.
Stellarium is pretty good, but in their FAQ and documentation they point to Cartes du Ciel as a better choice of software for such studies, citing the errors in their approach for stars like Sirius and Dubhe as only indicating the direction of motion, and change of shape of constellations - not the quantity or precise angle.
Still, it is very interesting to see how the stars appeared slightly differently in ancient skies…
Sopdet in situ today…
… vs 3000BC
(thanks to Cartes du Ciel)
I was going to start my epag days tomorrow, in line with Kemetic Orthodox Temple. But I am now sick with something suspiciously like Covid. I feel awful and the house is a mess. Certainly not in a celebratory mood. Not sure whether to shift dates or push through.
How horrid! I hope you feel better soon.
@Senneferet I also hope you feel better soon, and that it is just “suspiciously like” COVID rather than the real deal. Maybe these days are a good time to try and relax and recover?
I’m planning on starting the intercalary days tomorrow myself. Its poorly timed in my life as well, but I will do my best to take some time out and make suitable offerings.
Same! I’m also celebrating the epagomenal days from tomorrow. Hoping I can fit in my offerings.
What is that screenshot of?
a work in progress to be found here:
https://semiessessi.github.io/kemetic-calendar/
EDIT: I made a thread about it here
That calendar is coming along well. Looks good! I like what you’ve done with the intercalary days - sunrise and sunset.
It is the KO date for Wep Ronpet today.
I hope those who follow this date are having a good one. 
Happy Wep Ronpet again. For those of us celebrating it today,
Happy Wep Ronpet! 
I hope your celebrations have gone well.
I hope you had a wonderful celebration. Finally I consecrated my new shrine ( in my bedroom) for my Lady Serqet and several other Neteru 
Well I was going to go for the KO date but then due to relatives being here I went for Kemetic Reform date instead. I’m so undecided about when is the ‘correct’ date. I even saw 27 August is being the heliacal rising of Sirius here in the UK - is that correct ??
I need some kind of summary of all the versions and why those days are chosen by different groups / people.
Then what is the consensus of opinion? Do you go for the original date in Egypt, the current date in Egypt, the current UK date or something else ?
It’s so confusing!!
I can suggest this is possibly accurate, it depends on the latitude and the horizon. Having done the computations, automated them and verified them against as many sources as I could find… it is not an exact science whatsoever. Using the computation method from Ptolemy at our latitude and with modern models of the Earth’s orientation and an ‘arcus visionis’ of 10 degrees results in 29th August at Greenwich. The 19th August is the last date when they will rise with in the same hour, which sets a reasonable lower bound at least.
These values maybe more suitable for the hot and humid summer in Alexandria than today’s conditions, and my work with this leads me to believe that practical observations are likely to have a wide variance - perhaps as much as 15 days.
All that being said, the ancients resisted calendar reform for good reasons, and employed a wandering year, much more suitable for astronomical reckoning than for maintaining the dates of equinoxes. The heliacal rising date would drift once every 4 years or so (occasionally 3 or 5) to the next calendar date… and this was fine.
EDIT: … if i was going to have a stretch, there is no modern consensus and the Kemetic Reform and Kemetic Orthodox dates seem to come from trying to recreate a practise the ancients themselves stopped using before the Middle Kingdom.
I also have the opinion that no date is really right or wrong. Have you seen how many creation myths we have? 
I have the same opinion. I think it’s about what’s right for that person/group.
I wonder whether the festivals of Auset throughout the Roman empire were celebrated via a Roman calendar or local calendars depending on the position of the stars?
From what I’ve seen so far, only the first few years of Augustus used the traditional ‘wandering year’ as-is, during this time the Roman calendar was altered to correct broken reforms. In Egypt once the Alexandrian calendar was introduced, the Roman Julian calendar slowly caught up with it until 4AD (iirc).
That being said, the cult of Auset became popular in Rome before that, so I’d imagine there was certainly some ambiguity during the overlap.
There are also the celebrations and activities based off of the lunar calendar which are quite another thing and would constantly drift, whilst being held on the same day regardless of calendar.
EDIT: mentioning the Alexandrian calendar reminds me that the Coptic calendar is another fine descendant of the legacy that people may wish to follow. It certainly has a long history, and whilst it is not the original 360 day year with 5 extra days, it is the valid inheritor for a significant number of people.
