कालशोध · kaalshodh

आर्यभटीय · गोल यात्रा

an Āryabhaṭīya tour for Gol · Astro Lab

Each verse-cluster, as a running sky simulation


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Gītikāpāda · गीतिकापाद

Chapter 1 — the foundational constants

I.8

Obliquity of the ecliptic

The Sun's path tilted ~24° to the celestial equator; the ecliptic pole off the celestial pole.

I.9

Nodes — Rāhu & Ketu

The Moon's 5°-tilted orbit crossing the ecliptic at two nodes, where eclipses fall.

I.3

Revolution numbers (bhagaṇa)

Each body's coming cycle through the zodiac drawn as a dated trail; Mars's retrograde loop.

Golapāda · गोलपाद

Chapter 4 — spherical astronomy (the engine's home ground)

IV.1–5

Sphere & the ecliptic's halves

Equator, ecliptic, and the Sun walked through the four seasons.

IV.6–10

The Earth turns (the boat)

The whole framework wheels westward — from outside, then as an observer feels it.

IV.11–17

Laṅkā to Meru

The sky reshaping from the equator to the pole across a latitude tour.

IV.18–21

Reference circles

Horizon, meridian, prime vertical (samamaṇḍala), and the unmaṇḍala.

IV.23–26

Declination & day-circle

Solstice day-circles (dyujyā) and the equatorial RA/Dec frame.

IV.27

Cara — ascensional difference

The sunrise point migrating north and south through the year.

IV.28–32

Gnomon & shadow (śaṅku)

The Shanku Yantra: a gnomon casting its real shadow, and the Sun's amplitude (agrā).

IV.36

Precession (ayana)

The vernal point creeping westward through the nakshatras, century by century.

IV.37–46

Lunar eclipse (Bhūchāyā)

The full Moon at the node crossing the Earth's shadow-cone — the eclipse geometry.

IV.48

Conjunction check

Sun and Moon meeting at one longitude (new moon), then opposite (full moon).

Kālakriyāpāda · कालक्रियापाद

Chapter 3 — the reckoning of time

rising

Rising of the signs · lagna

The ascendant climbing the eastern horizon; signs of long and short ascension.

III.1–6

Panchang & intercalation

Nakshatras and tithis as the Moon sweeps the ecliptic; why adhimāsa is needed.

III.20–21

Direct & retrograde motion

Mars followed against the stars, halting and looping backward near opposition.