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

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.

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"They reasoned that an object situated at the center and related equally to the extremes in every direction can have no impulse to move in any specific direction. In fact, they compared the situation of such an object with that of a man violently but equally hungry and thirsty, standing at the same distance from food and drink and unable to decide in which direction to move." - Aristotle

This US Naval Observatory page on alt-az computations might help:

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

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Todd (Bowie, MD, US, North America, Earth, Sol System, Vega region, Local Bubble, Orion arm, Milky Way Galaxy, Local Group, Virgo A Cluster, Virgo supercluster, the universe in which spock is clean shaven)

Quidquid latine dictum sit, altum sonatur.

personal page: http://blog.astrosketches.info

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