For equatorial mounts, your two parameters are Declination and Right Ascension. Bill Ellis wb9cac@comcast.net ----- Original Message ----- From: "Chris" <nimbo@ukonline.co.uk> To: "List for Photo/Imaging Educators - Professionals - Students" <photoforum@listserver.isc.rit.edu> Sent: Wednesday, November 19, 2003 4:36 PM Subject: RE: Altazimuth telescope mounts correction > I think the other axis for equatorial is the altitude. A star is known from > its hour angle (round the equator from the first point of Aries) and > altitude (above the equator) > > Azimuthal is degrees down from the zenith (overhead) and the angle in > degrees round from north on the horizon. (no good if you are at the pole). > > Its all spherical triangles. > > You can convert from azimuthal to equatorial using a spherical triangle > computation (quite complicated but which I did know once but have forgotten) > or with an analogue computer consisting of potentiometers mounted on gimbals > in a complicated sort of way. They went out when digital computers came in. > > The conversion depends on where the telescope is on the earths surface and > assumes that the earth is spherical. > > I really like spherical triangles like every navigator should. All > forgotten now. Not that I ever did navigation for real, I've only held a > sextant a couple of times. > > Chris. > http://www.chrisspages.co.uk > > -----Original Message----- > From: owner-photoforum@listserver.isc.rit.edu > [mailto:owner-photoforum@listserver.isc.rit.edu]On Behalf Of ADavidhazy > Sent: 19 November 2003 18:45 > To: List for Photo/Imaging Educators - Professionals - Students > Cc: andpph@vmsmail.rit.edu > Subject: Altazimuth telescope mounts correction > > > Altitude and azimuth - thus they actually > have two axes of rotation. OK - sue me!! > > But then equatorial still stands methinks! > > :) > andy > > >
