What is a Zodiac Sign and How It's Calculated
Jerebok is a derived point in the chart, obtained by adding and subtracting longitudes. The general form is simple: the distance between two significant points is added to the ascendant, so Jerebok always depends on the birth time.
Arabic terms emerged historically, though the technique is older: lots were described in Hellenistic sources, and Arabic authors systematized them and greatly expanded the list.
- •The formula always relies on the Ascendant and two other points.
- •The ephemeris moves approximately 1 degree every 4 minutes of birth time.
- •Al-Biruni cites over 90 lots, later lists exceed 100.