Al-Ashraf ̔Umar’s Tabṣira, Chapter xxiii: Timekeeping at Night by the Moon in 13th-Century Yemen and Beyond

Abstract

This article explores methods for determining moonrise and moonset as evidenced within a range of pre- and early modern sources originating from Islamicate societies. The idea emerged during a workshop in July 2022 where a talk by the first author on Ibn Waḥshiyya’s moonrise-moonset text in his al-Filāḥa al-Nabaṭiyya («The book of Nabatean agriculture») and the second author’s project on the Kitāb al-Tabṣira fī ̔ilm al-nujūm («Book of enlightenment in the science of the stars») by al-Ashraf ̔Umar revealed overlaps. Given the resemblances observed in the two sources, chapter xxiii of Tabṣira has been selected as the initial reference point for tracing the technique across additional sources. It is important to note that this examination does not assert comprehensiveness, nor does it account for the reciprocal interdependencies among the examples presented. Nevertheless, the present article suggests a categorisation of the diverse methods predicated on various factors such as exactitude, complexity, state of completeness, literary formats, and audience.