Expert: Jayendra Upadhye - 11/11/2004

Question
I take the classical position that I am standing in the centre of a sphere, and the stars are on the surface of the sphere.
Taking the plane containing my meridian as a reference the location of a star can be described in terms of Hour Angle, Declination, Azimuth, Altitude, and the constant latitude ( and probably a hundred other quantities as well. Given that the stars are relatively slow moving is there another system for locating the stars that does not need to be updated for epoch every few years due to precession?)
Each of HA,Decl,Azi,Alt describe a plane in 3-space and the star is at the intersection of these 4 planes. Now as 2 planes intersect in a line and the stars location is on the surface of the sphere (giving one point or 2 symetrical points) it is only necessary to know any 2 of the 4 quantities to locate the star and to calculate the other 2 quantities.

There are 6 ways to choose 2 0f 4 quantities, and 2 quantities to calculate, and hense 12 equations to relate these quantities. What are these equations?


Answer
Hi matt,
I would have loved to answer your question ...
However a grave personal tragedy has overtaken me.
A person close to me has passed away and i am likely to be unavailable starting NOW, for a week.
Please bear with me.
You could pass on this question to any one of the other able experts listed for this category.
They will surely help you out.
Thanks and sorry for the inconvinience,
Jayen