This is Reason 3

Swiss ephemeris/True Chitra ayanamsha

The Swiss ephemeris pulls planetary and moon data from NASA’s Jet Propulsion Laboratory. It spans from 13201 BC to AD 17191 and is considered to be the most precise ephemeris currently available.
To read about the Swiss ephemeris in more depth visit www.astro.com/swisseph/swephinfo_e.htm
True Chitra ayanamsha assumes the star Chitra, known as Spica in western astronomy, is exactly 180 degrees at all times. This ayanamsha is a refined version of the Lahiri ayanamsha, which considered Chitra to wobble around 180 degreed rather than being fixed there. Since the ayanamsha calculation takes the point directly opposite Chitra into account when determining planetary positions, whether the star wobbles or is fixed changes the calculations.

To use the True Chitra ayanamsha, you must manually select it, as the Lahiri ayanamsha is set as the default in Parashara’s Light. See the “How to” section below for instructions.

Consider switching to the True Chitra ayanamsha, as it is more accurate than the widely accepted Lahiri ayanamsha.

To set the Ayanamsha to True Chitra:
1. Go to the Options drop down menu and select Calculation options

2. Under the Ayanamsha column on the left, select True Chitra

3. Press OK to save the new setting and recalculate the charts.