Kiya Nicoll, author of The Traveller’s Guide to the Duat: Amenti on Two Deben a Week
wrote a blog post about the calculation of calendars and the position of Sopdet.
The post is here: I Love it when a plan comes together
What she found out was that the date where the sun and Sopdet are closest? Aset Luminous.
If anyone is interested, here are links to Kiya’s book:
From Megalithica Books: Traveller’s Guide to the Duat
From Amazon (Paperback): Traveller’s Guide to the Duat