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pkay
2007-Oct-04, 07:04 AM
I am trying to write a program for my programmable calculator to calculate elevation / azimuth of an object (for my location and time) given Right Ascension and Declination.

I have a formula that requires the Greenwich Hour Angle of the Equinox at Jan 1, 2007 and I cannot seem to work out how to obtain it. Any clues?

If not does anyone have another formula?

Thanks in advance.

Regards
Peter

a1call
2007-Oct-04, 01:21 PM
You can have Equinox times UTC /Greenwich here:

http://en.wikipedia.org/wiki/Equinox

You will need that value or something equivalent for the formula to work.

tdvance
2007-Oct-04, 05:35 PM
This US Naval Observatory page on alt-az computations might help:

http://aa.usno.navy.mil/faq/docs/Alt_Az.php

Tobin Dax
2007-Oct-04, 06:07 PM
This US Naval Observatory page on alt-az computations might help:

http://aa.usno.navy.mil/faq/docs/Alt_Az.php

That looks pretty good. A *lot* better than the astronomical almanac. That thing's darn near impossible to read. :eek: