Fourth Workshop April 2017


Matthieu Husson (CNRS, SYRTE-Observatoire de Paris)

Date: April 20-21, 2017

Place: Observatoire de Paris, batiment Perault, Salle du conseil

Short presentation

Continuing the work began during the third workshop this 2 days meeting will also address two objectives. It is first an opportunity to hear three young scholars presenting their research and projects with respect to astronomical tables. Second it will be the occasion to refine the discussions concerning the structure of the table database in particular with respect to the format(s) used for number storage, computations and display.



April 20, 2017


Salle du Conseil

8h50-9h00 Introduction

Matthieu Husson


9h00-10h10 Methods and practices in recomputing mathematical and astronomical tables: A preliminary case study of the sine tables from Nityānanda’s Amṛtalaharī.

Anuj Misra (Post-doc, TAMAS project, SYRTE-Observatoire de Paris)

In presenting recomputed versions of numerical tables, quite often, the technical decisions about choosing an appropriate computational method, selecting a suitable rounding scheme, or even establishing a credible theoretical source for the algorithms are not fully discussed. Understanding the context and content of these decisions can help understand the process of table-cracking in practice. In this presentation, I discuss my analytic technique to recalculate the sine values of Nityānanda’s Amṛtalaharī (c. 1630) in an effort to explore the procedure, the challenges and the limitations in recomputing numerical tables.


10h10-11h20 Adapting and Importing Astronomical Tables in Byzantium (14th-15th centuries)

Jean Lempire (Post-doc, Université Catholique du Louvain)

Greek manuscripts of the late 14th century and the 15th century present various collections of astronomical tables. This brilliant period of the Byzantine astronomy is characterized by a renewed interest in the study and the practical application of Ptolemy’s works. Along with this scientific trend, the Byzantines import a lot of astronomical texts and tables with a foreign background. In addition to Ptolemy’s tables – the Handy Tables especially –, that have been widely copied and sometimes modified by Byzantine scholars, manuscripts offer numerous Greek adaptations of Persian, Latin and Jewish tables. In this extensive matter, my purpose is to focus on some rich topics: the New Tables of the Byzantine scholar Isaac Argyrus (who flourished in the last third of the 14th century), the Greek adaptation of Jewish astronomical treatises (Hexapterygon of Michael Chrysoccoces, about 1435) and the adaptation of Alphonsine tables (Treatise on Latin Tables of Demetrius Chrysoloras, 1380).


11h20-11h30 coffee break


11h30-12h40 Equation tables in the Dṛggaṇita of Parameśvara

Sho Hirose (Post-doc, Swiss Federal Institute of Technology,

The Dṛggaṇita (1431-32 CE) by Parameśvara is a versified text that contains various methods and parameters for astronomical computation. The treatise is said to have largely replaced the preexisting set of values and computational procedures, which is referred to as the Parahita system today. The standard explanation is that Parameśvara improved the Parahita system using his own astronomical observations, but not enough studies have been made to ground this from the side of the values within the texts. Furthermore, no record of astronomical observations by Parameśvara related to planetary positions survive today.

In this study I shall focus on a set of versified tables for planetary equations in the Dṛggaṇita. This appears in the second part of the treatise, which is “intended for young learners” according to the author. The first part gives a method for computing the planetary equation, which might also have been used for producing the table. In addition, Parameśvara seems to have worked on revising his text, and one of the manuscripts seems to have been derived from a preliminary draft or an earlier version. There are significant differences in the table of this manuscript which are to be examined. From these materials I attempt to analyse how Parameśvara completed his table, which in turn shall be the first step for finding the connection between the Parahita system and the Dṛggaṇita.


12h45-13h45 Lunch


Bat. B rdc

13h45-17h00 Database discussion: number format ?


April 21, 2017

Salle du conseil

9h00-12h30 Database discussion : number format ?


12h40-13h40 lunch


13h45-16h45 Open discussions