Ascendant (Lagna) Calculator

What is the Ascendant (Lagna)?

The Ascendant, also known as the Rising Sign or Lagna in Vedic astrology, is the zodiac sign that was ascending on the eastern horizon at the time of your birth. It represents your outward behavior, physical appearance, and the way you interact with the world. The Ascendant is a crucial component of your birth chart and is considered as important as your Sun and Moon signs in determining your personality and life path.

The Formula for Calculating the Ascendant

The calculation of the Ascendant involves several steps and astronomical formulas:

1. Convert birth date and time to Julian Day (JD)
2. Calculate Greenwich Mean Sidereal Time (GMST): \[GMST = 280.46061837 + 360.98564736629 * (JD - 2451545.0) + 0.000387933 * T^2 - \frac{T^3}{38710000}\] where \(T = (JD - 2451545.0) / 36525\)
3. Calculate Local Sidereal Time (LST): \[LST = GMST + Longitude\]
4. Calculate Ascendant: \[Ascendant = \arctan2(\cos(LST), \sin(LST) * \cos(\epsilon) - \tan(\phi) * \sin(\epsilon))\] where \(\epsilon\) is the obliquity of the ecliptic and \(\phi\) is the observer's latitude

Where:

• JD = Julian Day
• GMST = Greenwich Mean Sidereal Time
• LST = Local Sidereal Time
• \(\epsilon\) = Obliquity of the ecliptic
• \(\phi\) = Observer's latitude

Example Calculation

Let's calculate the Ascendant for a birth on August 15, 1990, at 14:30 in New Delhi, India (longitude 77.209021°):

1. Julian Day: 2448119.10417
2. GMST: 333.3982°
3. LST: 50.6072°
4. Ascendant: 155.7234°
5. Zodiac Sign: Virgo (5.72°)

Visual Representation

This circle represents the zodiac wheel, with the Ascendant sign and degree at its center.