ESAC SOHO Science Archive Tutorial

Rearrange the formula to find the latitude:And the longitude:− ⎛Latitude = sin 1 ⎜⎝− ⎛Longitude = sin 1 ⎜⎝( y − CENTER _ Y ) ⎞ ⎟R _ Sun( x − CENTER _ X ) ⎞ ⎟R _ Sun⎠⎠Note: The formulae are approximated and more or less valid for small latitudes.However, we are actually calculating the longitude and latitude of points on asphere (see images below). It would therefore be better to use sphericaltrigonometry, which, to calculate the longitude, approximates to: multiply x withthe cosine of the latitude to find a new X, and then compute the longitude applyingthe formula above, substituting x for X.17