Rājamṛgāṅka (astronomy book)

Rājamṛgāṅka is a treatises in Sanskrit devoted to astronomical computations. Traditionally the authorship of the treatise is attributed to Bhojarāja (d.1055) of the Rajput Paramāra dynasty, rulers of the Malwa region in central/western India. The work exists in widely varying versions and an authoritative original text has not yet been established. However, a provisional critical edition was published by David Pingree in 1987. It is possible that the book may have been produced in collaboration with one or several court astronomers. If so, a definitive original text may never have existed in a unique form. Whatever, the Rājamṛgāṅka’s epoch date has been firmly determined as 23 February 1042.

Rājamṛgāṅka follows the Brāhma-pakṣa school. This school uses the values of the fundamental parameters, namely, the values of the celestial bodies’ revolution-numbers and consequent mean velocities, as given in the Brāhmasphuṭasiddhānta of Brahmagupta composed in 628 CE. The work identified itself as a karaṇa text, that is, a text that deals exclusively with the computational aspects of astronomy. But in fact it not a pure karaṇa text; it could be best described as a hybrid karaṇa-koṣṭhaka text. There is a significant difference between Rājamṛgāṅka and other karaṇa texts in that the former has given extensive tables of values for ease in computation where as the traditional karaṇa texts do not provide such table. In this sense, Rājamṛgāṅka has been described as the first noteworthy astronomical table text in Sanskrit.

Rājamṛgāṅka has had some impact on the subsequent Sanskrit astronomical literature. It influenced the writing of the first known Sanskrit astronomical table text (a koṣṭhaka text) Grahajñāna by Āśādhara in 1052. It also influenced Bhāskara II's Karaṇakutūhala as some of the algorithms in Karaṇakutūhala can be seen as adaptations and developments of certain algorithms in Rājamṛgāṅka. But the koṣṭhaka format of Rājamṛgāṅka had absolutely no impact on Karaṇakutūhala