NavList:

I’ve been thinking about this latitude from equal altitudes business. There must be an easier way than fiddling around with Navigator or Stellarium, which incidentally give similar but different solutions for an observer in the Southern Hemisphere. I’d like to try and work it out without opening a textbook or going to Google. So far, it seems to me that if Rigel and Alnilam are level to the observer, they must have tipped their visual horizon with respect to the celestial equator by an amount equal to their latitude, or maybe their co-lat; I’m still trying to fathom that out. I tried working it out using flat trig, and it didn’t work (unless the film was really shot near Hollywood), so I’m now intending to try spherical trig if I can still remember how to do it DaveP

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