Calendar Tradition Settings: Ayanamsha, Masa System, and Horizon Type

Under Settings → Calendar Tradition, there's an "Advanced" row that most users never tap. It reveals three calculation parameters that affect how your panchang is computed. For most people the defaults are correct — but if you follow a specific Jyotisha school or regional tradition, these settings matter.

Calendar Type: Smartha / Vaishnava / Shaiva

This is the most commonly changed setting. It controls which festival dates and Ekadashi calculation rules the app uses:

• Smartha — Classical Advaita calendar. Standard Ekadashi and festival dates per traditional panchang rules. Default for most users.
• Vaishnava — Gaudiya Vaishnava / ISKCON calendar. Ekadashi is observed on the correct day for strict fasting per Hari Bhakti Vilasa rules, which can differ by a day from the Smartha date. Also includes Gaura Purnima, Rath Yatra, and Chaturmas markers.
• Shaiva — Highlights Pradosh Vrat, Masik Shivaratri, Skanda Sashti, and Shaiva-specific observances.

Masa System: Amanta vs. Purnimanta

This setting controls how the lunar month is named and when it begins:

• Amanta — The month ends on Amavasya (new moon). Month names are based on the nakshatra of the full moon within the month. Widely used in South India, Maharashtra, and Gujarat.
• Purnimanta — The month ends on Purnima (full moon). The same calendar events occur but fall in differently named months. Standard in North India, particularly in the Hindi-speaking states.

This setting affects masa (month) labels throughout the app. The underlying tithi, nakshatra, and muhurat calculations are identical — only the month name changes.

Ayanamsha: Lahiri / Raman / Krishnamurti (KP)

Ayanamsha is the correction applied to convert tropical (Western) planetary longitudes to the sidereal zodiac used in Vedic astrology. Different schools use slightly different ayanamsha values:

• Lahiri (Chitrapaksha) — The official ayanamsha of the Government of India and the most widely used in traditional Jyotisha. Default setting. Currently approximately 23°47'.
• Raman — Developed by B.V. Raman, slightly different from Lahiri. Used by practitioners following the Raman school.
• Krishnamurti (KP) — Used in KP (Krishnamurti Paddhati) astrology, a more precision-oriented system. If you use KP for horary or electional astrology, switch to this setting.

Changing the ayanamsha shifts all planetary longitudes slightly, which can change house cusps, nakshatra positions near boundaries, and occasionally the Lagna itself for borderline birth times. Unless you follow a specific school that uses Raman or KP, leave this on Lahiri.

Horizon Type: Astronomical / Apparent / Geometric

This controls how sunrise and sunset are calculated — which affects every time-based panchang element:

• Astronomical — Uses the center of the Sun disk and accounts for atmospheric refraction. The most precise method and the default.
• Apparent — Uses the upper limb of the Sun (the moment the first edge appears above the horizon). This is what many traditional pandits and almanacs use — the visible sunrise, not the geometric one.
• Geometric — Pure mathematical sunrise without refraction correction. Used in some calculation traditions.

The difference between Astronomical and Apparent is typically 1–3 minutes, which is enough to occasionally shift a Choghadiya boundary. If you notice your app's sunrise differs from a printed almanac, Horizon Type is often the explanation.