How to efficiently determine if certain azimuth heading is crossed during satellite pass in SkyField

Question

I am trying to determine if an upcoming satellite pass in SkyField will cross a certain azimuth heading, say 0.0 deg north. Right now I iterate in 1 sec steps "manually" over the entire pass from risetime to settime to check if the azimuth heading crosses 0.0 degrees. However this approach is very inefficient and takes too long for satellites in MEO/HEO with long passes.

Does anyone have a better approach how this could be achieved?

(Background story is I have a tracking platform which has limited azimuth range due to cable wrap from 0.0 - 360.0 so I need to know if the satellite pass will cross through north, in which case I flip the pass to not be limited by the azimuth travel limit.)

Answer 1

Not sure this will help you as I'm quit new to astronomy and just getting my feet wet with Skyfield. My approach for testing for specific satellites that could pass in my sky were as follows. I use geocentric = iss.at(times), subpoints = geocentric.subpoint() to determine the geographic position elements (latitude, longitude, elevation) assuming these are ground track figures. I then test if the figures fall within the bounding box I defined loosely based upon the horizon distance formula. My bounding box is about half of what the distance formula suggests thus I'm assuming the great circle distance will always be less than the horizontal distance and within my bounding box. I retain only those geographic positions that meet the above criteria with also the addition of being within evening hours. I have yet to validate my findings as they are still off from info I'm finding on other sites for satellites of interest to me. Haven't figure out yet the discrepancies but I believe the approach is sound in narrowing down the potential set of satellites over my area.