In astrology we use declinations since the very start of horoscopy. Not just for parallel aspects but also for more sophisticated systems like the one defined by Kt Boehrer. Even in archaeo-astronomy you will need declinations to define the position of a planet at the horizon. At RadixPro you will now find formulas to calculate the declinations yourself: Declinations
For almost all calculations you need to know the value of the angle between equator and ecliptic. That angle is relatively constant but over longer periods of time the value does change. You can handle these changes now: at RadixPro you will find formulas for the calculation of Epsilon as this angle is called by astronomers.