NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: "Vernier acuity" of horizon IC tests
From: Douglas Denny
Date: 2009 Jul 7, 01:19 -0700
From: Douglas Denny
Date: 2009 Jul 7, 01:19 -0700
"Those statistics strongly suggest (though are not yet conclusive) that there's a real difference between the index zeros, depending on the telescope that's in use. If that's really the case, can anyone suggest a possible physical cause? It eludes me." ------------- The answer most likely is: Slight prism effect through the telescope system if not viewed directly down the parallactic centre axis. If looking slightly offset from centre-line then prism effect will shift the apparent axis. It does not require much of an offset from the optical centre to give a large effect of prism in powerful optics. Douglas Denny. Chichester. England. --~--~---------~--~----~------------~-------~--~----~ Navigation List archive: www.fer3.com/arc To post, email NavList@fer3.com To , email NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---
