Comment by lukas9

The other guy is not wrong... kinda. I used AI for the code because I have no experience with Swift and SwiftUI, but I do understand how the calculations work, because I designed them. CelesTrack gives me TLE data, precisely describing each satellite's orbit and movement, as well as its current position on the orbit. What my app does is simply simulate the satellite's position (in 30-second intervals) up until 2 or 7 days into the future, and checks whether the satellite is overhead on each interval. Satellites are considered overhead based on just one criterion, and that is that they are above your horizon (so an elevation > 0 degrees). Hope that answers your question.