IKS Series : Book-3
Ancient Indian Astronomy
Chapter-1: Introduction to Vedic Astronomy and Basic Time Divisions
Overview of astronomy in the Vedas; fundamental divisions of time including years, months, and days.
Chapter-2: The 13 Months in Taittirīya-Brāhmaṇa
Detailed names and astronomical/ritual significance of the 13 lunar months as described in the Taittirīya-Brāhmaṇa.
Chapter-3: The 12 Half-Months (Pakṣas) in Vedic Timekeeping
Examination of the 12 half-months (bright and dark fortnights), their nomenclature, and role in structuring the lunar calendar.
Chapter-4: Structure and Length of the Lunar Year
Analysis of the 354-day lunar year (12 lunar months), its synchronization challenges with the solar cycle, and basic implications.
Chapter-5: Intercalary Months and Lunar-Solar Synchronization
Concept of adhika (intercalary) months; mechanisms to align lunar and solar years in Vedic and post-Vedic systems.
Chapter-6: General Time Measures and Units in Indian Astronomy
Historical evolution of time units; from Vedic micro-units to broader astronomical scales.
Chapter-7: Modes of Reckoning Time: Lunar Day and Solar Day
Detailed comparison of tithi (lunar day) and sāvana (civil/solar day); reckoning methods and differences.
Chapter-8: Solar Year, Lunisolar Year, and Civil Day
Definitions, calculations, and practical uses of solar year, lunisolar year, and civil day in Indian traditions.
Chapter-9: Conversion Between Major Indian Eras
Algorithms for converting dates across eras: Śaka to Kali, Śaka to Jovian (Bṛhaspati) years, Vikramasaṃvat to Kali, Kollam year to Kali.
Chapter-10: The Pañcāṅga: Foundation of Indian Calendrical Systems
Introduction to the five limbs (elements) of the Pañcāṅga and their role in traditional almanacs.
Chapter-11: Computations of Pañcāṅga Elements: Nakṣatra, Tithi, Yoga, Karaṇa, and Vāra
Step-by-step methods for calculating nakṣatra, tithi, yoga, karaṇa, and vāra (weekday).
Chapter-12: Solar Nakṣatras and the Solar Calendar System
Nakṣatra alignment with the Sun; structure and features of purely solar calendars in Indian astronomy.
Chapter-13: Major National and Regional Eras in Modern Context
Overview of Vikramasaṃvat, Śālivāhana-Śaka (national calendar basis), and the Rāṣṭrīya Dinadarśikā (National Calendar).
Chapter-14: Planetary Computations in Siddhāntik Texts: Āryabhaṭīya Basics
Ahargaṇa (elapsed days) computation; revolution numbers of planets in a Mahāyuga from Āryabhaṭīya.
Chapter-15: Mean Longitudes and Corrections: Mandasaṃskāra and Śīghrasaṃskāra
Calculation of mean planetary longitudes; application of manda (equation of center) and śīghra (equation of synodic anomaly) corrections to derive true longitudes.
Chapter-16: Evolution of Planetary Models, Ayanāṃśa, and Simplified Systems
Development from Āryabhaṭa's geocentric model to Nīlakaṇṭha Somayājī's quasi-heliocentric revisions; various ayanāṃśa (precession) determination algorithms; simplified planetary positions via Karaṇa texts (e.g., Karaṇakutūhala, Grahalāghava); Candravākyas of Vararuci and Mādhava with error-correction procedures; Vākya system for Sun/Moon longitudes; significance of Māsavākyas, Saṅkrānti-vākyas, and Nakṣatra-vākyas.
Professional Note
Authors may submit chapters other than those listed above, provided the proposed chapter aligns with the overall theme and objectives of the book.