Determination of the date of the First Point of Aries held fixed using a combined method of Astronomy and Astrology

In the pre-era of the Global Navigation Satellite System (GNSS), Astronomy was the only technique available for the determination of position or Azimuth. Still, to understand the space-based technique, a good knowledge of Astronomy is necessary; the concept of the Celestial Sphere, Coordinates of Celestial Bodies, and the various categories of Time. The celestial coordinate systems are based on the fixed point in the space, the Vernal Equinox or the First Point of Aries(γ). This point is not static and has a backward movement of about 50 arc seconds per year. In the Eastern system of Astrology, this point is held fixed, but the date it was held fixed is uncertain. This article describes a method to determine this date by using Astronomical and Astrological calculations. According to the computations based on Julian days and the longitude of the Sun, it was found that the First Point of Aries was held fixed around 420 AD.