I've never seen several concepts integrated so perfectly in one story. I'm not into archaeology, but this made me look up some details. It marvelled me how meticulous the preparations of archaeologists during their excavation seasons! No wonder Ephraim wanted to go to Cairo.
Also, I'm a nerdy of astronomy, primarily on cosmology. This novel just keeps on dishing out facts like a freakin' black hole with its hawkings radiation. That Arthurian legend is probably a disguised theory, one that I've definitely read but can't remember somehow.
You included extensive facts and surprisingly, they are not out of place. They were purposefully placed, which aided in the learning of the readers. We're discovering things along with Ephraim. Lucian better look at that x-coordinate.
My favourite character here is definitely Samuel. Others might favour Bertholdt for his casual maturity, Esmeralda for her cuteness and intellect, Hiroaki cause he's a badass, or Ephraim for his reasonableness. However, Samuel is being true to himself, being merely a kid in the midst of accomplished adults. I don't mind his sharp, unreasonable tongue, since, maybe, it's his defence mechanism. He chose to be there for his sister and that's commendable!
Some of us will definitely relate to having Joanna as a parent, and you conveyed her adamant refusal to what Ephraim really wanted for himself. It's painful reading this; it is so relatable!
The characters are well established, making the readers feel like we know them personally. They are very distinguishable in every passage! I utterly love your story! Please be my Ephraim and teach me!
I will be supporting! Best wishes to you, author! Sorry for the lengthy review!