NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Jupiter's moons
From: Herbert Prinz
Date: 2002 Mar 21, 00:51 +0000
From: Herbert Prinz
Date: 2002 Mar 21, 00:51 +0000
Nigel, I believe this is a misunderstanding. Sighting pieces differ mainly in magnification, field of view and light power or whether the image was erect or inverted depending on whether they were optimized for observing the Sun or the stars, on a steady deck or in a seaway, or for altitudes or distances. None were suitable for Jupiter satellite observation. Why would one want to observe satellite phenomena with a sextant, anyway? It's difficult enough with a suitable telescope. Try to watch (never mind timing!) Jupiter's satellites with your regular binoculars, and you will see what I mean. Sighting pieces are and were certainly not better than modern binoculars. By the way, does Riddle really say "occultations" ? He sure means "eclipses", doesn't he? Nigel_Gardner wrote: > Herbert wrotemagnification do/did > these sighting pieces have?> > > I am afraid I have not, in UK decent old sextants have been priced out of > navigators' markets by being bought up by chi-chi antique dealers to sell > to people to hang on a wall. My own 'good' sextant is a modern Zeiss but > with only one eyepiece. > I looked in my copies of Nories Epitome (one 1805 and the other 1896) which > give good, long and lucid descriptions of sextants. Both descriptions say > that a sextant is normally equipped with two magnifying eyepieces of > different strengths but neither sadly give any indication of what the > stengths are. > > NG