Hi Holger Isenberg,
Firstly i will deal with your pm and if i was aware that Sirius doesn't move against the backdrop of precession, this only works with the Julian Calendar which isn't accurate it is out by approx. 3 leap days every four hundred years, however Sirius is a stunning example of shaping our calender, i am leaving a link to an astrology forum that i wrote about this, but i am an archaeoastronomer and study beliefs.
I do have spinal injuries being paraplegic, and typing is hard work, therefore i'm hoping to be allowed to paste from my own work here to explain the full explanation of your questions regarding many solar calendars.
I am aware of Stellium and you will find that my graphs accurate to it, i have checked.
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skyscript.co.uk]