The role of diagrams in Sanskrit astronomical manuscripts is a complex interplay of presence and absence. While often appearing as mere accessories, these diagrams, when present, are intricate visual representations of celestial phenomena. This talk delves into the variations in these diagrams, examining how different scribes have interpreted and copied the same diagram for various purposes and contexts.

By analysing the astronomical drawings in Nityānanda's seventeenth-century "Sarvasiddhāntarāja", we can develop a representational ontology of categories, conventions, perspectives, and pictograms that can inform our understanding of astronomical diagrams more broadly. This approach allows us to appreciate the dynamic and multifaceted nature of diagrammatic practices in Sanskrit astronomy.

From the 5th century onward, Sanskrit astronomical and mathematical commentaries prescribe the construction of diagrams involving circles and segment of arcs when reasoning on ways to approximate lengths of arcs and of their subtending (half-)chords.
In this presentation i would like to contrast the work on diagrams that can be found in these early commentaries, such as in Bhāksara's 7th century commentary on the Āryabhaṭīya (499) or Pṛthūdhaka's 9th century commentary on the Brāhmasphuṭasiddhānta (628) with what can be observed in Śaṅkara Vāriyar (fl.ca. 1540)'s famous proof of Mādhava's rule to approximate the circumference of a circle with an indefinite sequence in his commentary on the 12th century *Līlāvatī*. This presentation will more largely analyze the function of diagrams in relation to proofs and the different ways in which they embody ideas of generality, according to these different authors of Sanskrit mathematical/astronomical commentaries. In other words, it will describe a diversity of practices of diagrams.

Diagrams are very effective devices that are used for presenting data in astral and mathematical sciences. They aid to visualize phenomena and to calculate various properties of them. Hence, use of diagrams has been a practice of astral and mathematical sciences in all civilizations throughout the history. Indian astro-mathematicians too have been using diagrams from antiquity and these diagrams, at times, have been produced and reproduced in their pictorial form in manuscripts of original texts and their commentaries by respective authors, or scribes. However, in case of many texts, only verbal instructions are available, neither has the author/s of the original text and commentaries nor scribes illustrate them in the manuscripts. What is fascinating is that some commentaries consist of very descriptive information about diagrams in verbal form which may help readers understand what is in fact, being discussed in the original text. Makkibhaṭṭa’s (14th cent. CE) Gaṇitabhūṣaṇa, the one and only commentary on Śrīpati’s Siddhāntaśekhara is one of such commentaries. This has survived partially, but existing portion betrays thorough explanations on how to construct diagrams while the Siddhāntaśekhara does not even refer to them. Most of these diagrams seem to have been drawn on the floor using gnomon and rope/s as complementary to the original text and the commentator’s verbal commentary. We intend to discuss the commentaries on a few verses and make an attempt to reconstruct the diagrams on the basis of verbal instructions therein.