The Ascensional Difference is the difference between Oblique Ascension and Right Ascension.
The formula for computing the Ascensional Difference
Sin C = Tan Phi Tan Delta
where C is the Asc difference Phi is the Latitude of the place and Delta the Sun’s declination
The Sun’s declination can be found out by the formula
Sin J = Sin L Sin w
where J is the Sun’s declination, L the mean longitude of the Sun and w Sun’s maximum declination