Algorithm for apparent place computations.

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Дата изменения: Sat Oct 16 10:33:03 2004
Дата индексирования: Mon Oct 1 21:20:27 2012
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Поисковые слова: n02

Computer Ephemeris. Algorithm for apparent place computations. Explanations.

For calculation of apparent place of some star there are two methods. One of them is to use our tables from 'Apperent places ...' pages and then interpolate data to moment necessary. The second method is to use formulae of this page together with information from 'Mean places ...' and 'Reduction quantities' pages.

The formulae are:

ALPHAapparent = ALPHAmean + (A+A') * a + (B + B') * b + C * c + D * d + E + MUalpha * tau + tg²(DELTAmean) * J_a

DELTAapparent = DELTAmean + (A+A') * a' + (B + B') * b' + C * c' + D * d' + MUdelta * tau + tg(DELTAmean) * J_d

Here: ALPHAmean, MUalpha - mean right ascension and mean proper motion in right ascension of some star at mean epoch of the year,

DELTAmean, MUdelta - mean declination and mean proper motion in declination of some star at mean epoch of the year,

A, A', B, B', C, D, E - first order reduction quantities,

J_a, J_d - second order reduction quantities,

tau - interval from moment necessary to mean epoch of the year, designated as T_m on the 'First page', expressed in julian years.