NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Digital Camera Celestial Navigation
From: Frank Reed
Date: 2008 Jul 07, 16:49 -0400
From: Frank Reed
Date: 2008 Jul 07, 16:49 -0400
Paul Hirose, you wrote: "After some debugging, I realized there was nothing wrong with my code. Refraction reduces the semidiameter in every direction. When the left and right limbs refract up, they move on great circles which converge at the zenith. With a body of 16' semidiameter, and sea level refraction,this decreases the semidiameter about .27". I tested this at several altitudes from 10 degrees to 80, and it didn't vary more than .01"." What happens when you place the Sun at a true altitude of -30' so that refraction is just enough to lift it above zero degrees observed altitude? By the logic of great circles converging at the zenith, which sounds reasonable to me, shouldn't refraction then slightly increase the diameter of the Sun in this case (the diameter measured parallel to the horizon, that is)? I've never worked it out myself. I'm just asking. -FER --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
