Re: How can I calculate the Azmuth of the sunrise (set) based on date and lat?

There's an easy way and a hard way to figure out exactly where the sun (or any celestial object) will be on a particular date, as seen from a particular location.

The easy way is -- as you yourself mentioned -- to use one of many websites or planetarium programs to do the dirty work for you. Examples are:

• Sun and Moon information for one day
• JPL's Horizons ephemeris system for asteroids and planets
• Wunderground.com's planetarium site

There are many more websites, plus many programs you can run on a computer or PDA to tell you exactly where to look at any time and date to see any object. I recommend this simple, easy solution.

But, if you really want to know how to do it all yourself, you can try the hard way. There are several very good books which will both explain the mathematics and provide computer programs you can modify to suit your needs. I recommend:

• Astronomical Algorithms by Jean Meeus
• Astronomical Formulae for Calculators by Jean Meeus
• Practical Astronomy with your Calculator by Peter Duffett-Smith

These books will include references to the really technical literature, in case they aren't enough for you. But I suspect that they will be ....