The Red Pyramid's slope angle is 43' 22" [sites.math.washington.edu
]. Actually almost identical to the angle between the two largest Giza pyramids from the N/S axis of the layout (which itself is a few arc minutes West of North), 43 26' from my CAD replica from Petrie's data. It's simply the angle of the line between Merope and Electra when Electra was due West just before setting in the 4th Dynasty time period. Maybe they would watch to see when those two stars aligned with the North slope of the Red Pyramid. Then they would know when Electra was due West and could use it for alignments. Or could be coincidence, but a seemingly unlikely one. The basis for the 54 27' 44" slope of the lower part of the Bent Pyramid is unknown to me. Maybe you could find two other stars that produce that angle at a particular time
Edited 3 time(s). Last edit at 08-Oct-17 14:50 by V_Starling.