Transit of sun through the seasonal nakṣatra cycle in the Vṛddha-Gārgīya Jyotiṣa

Abstract

Vṛddha-Gārgiya-Jyotiṣa (VGJ) is an important text of Indian astral sciences before the astronomy texts of the Common Era. Only a few of the chapters of this text have been edited and published so far. The present paper reports an important study of two sections of this text which describe the transit of Sun along the 27 asterisms (nakṣatra) during the six seasons beginning with winter. The first section called Ādityacāra describes each season to be covered by Sun travelling 4½ asterisms starting from śraviṣṭhā nakṣatra at the beginning of śiśira ṛtu reckoned as the winter solstice day. The seasons are stated in terms of Sun transiting the beginning, middle and end of nine asterisms some of which are made of more than one star. The second section of the text known as Ṛtusvabhāva starts with the vasanta ṛtu and names twelve asterisms through which Sun transits in the 12 months of the tropical year. It is shown that the solar transit information in the Ādityacāra and the Ṛtusvabhāva chapters of VGJ can be dated, for minimum observational error, to c 1300 BCE and c 500 BCE respectively.