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Unformatted text preview: Summary of coordinate conversion formulae AST 3722  Spring 2008, Handout #5 1. Basic formulae for spherical trig. Consider a sphericaltriangle with sides a, b , and c , and with opposite angles A, B , and C . There are two basic formulae to remember: sin a sin A = sin b sin B = sin c sin C , and cos c = cos a cos b + sin a sin b cos C ; cos b = cos a cos c + sin a sin c cos B ; cos a = cos c cos b + sin c sin b cos A. These are the law of sines and the law of cosines. There are really only two formulae here – no need to remember every combination. 2. Equatorial to Horizon coordinates. Let H and δ be the hour angle and declination. We cannot use the right ascension α , but we’ll see later on that there’s an easy relationship between α and H . The hour angle is defined as the amount of time before or after the object has transited. When an object rises, it has 12h < H < 0 (or equivalently, 12h < H < 24h). H increases through the night. At transit, H = 0. When an object sets, 0= 0....
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This note was uploaded on 11/09/2009 for the course AST 4700 taught by Professor Fernandez during the Spring '09 term at University of Central Florida.
 Spring '09
 Fernandez
 Astronomy

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