• Boris A. Rosenfeld
Living reference work entry

Abū ḥāmid Aḥmad ibn Muḥammad al-Ṣāghānī al-Asṭurlābī was an Arabic astronomer and mathematician. He was born in Chagaian (Central Asia) and worked in Baghdad.

His main work was the Kitāb fī’l-tasṭīh al-tāmm(Book of the Perfect Projection on to a Plane) which is extant in two manuscripts. The treatise is devoted to a generalization of the stereographic projection of a sphere onto a plane, usually used in the making of astrolabes. This concerns the projection from a pole of the sphere onto the equatorial plane or a plane parallel to it. Under this projection, circles on the sphere are imaged onto the plane as circles or straight lines. The “perfect projection” invented by al-Ṣāghānī is the projection of the sphere from any point of its axis onto a plane orthogonal to the axis. Under this projection, circles on the sphere are imaged on the plane as conic sections (ellipses, hyperbolas, and parabolas) or straight lines. These descriptions of methods for conics construction are important...


Line Produce Equatorial Plane Construction Method Mathematical Treatise Stereographic Projection 
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  1. Frank, J. (1918). Zur Geschichte des Astrolabs. Sitzungsberichte der Physikalisch-Medizinischen Sozietät zu Erlangen, 48–9, 275–305.Google Scholar
  2. Hogendijk, J. P. (2001). The contributions by Abu Nasr ibn Iraq and al-Saghani to the theory of seasonal hour lines on astrolabes and sundials. Zeitschrift Fur Geschichte Der Arabisch Islamischen Wissenschaften, 1–30.Google Scholar
  3. Lorch, R. (1987). Al-Saghānī’s treatise on projecting the sphere. Annals of the New York Academy of Sciences, 500, 237–252.CrossRefGoogle Scholar
  4. Matvievskaya, G. P., & Rosenfeld, B. A. (1983). Mathematicians and astronomers of medieval Islam and their works (8th–17th C.) (Vol. 2, pp. 162–163). Moscow: Nauka (in Russian).Google Scholar
  5. Puig, R. (2014). Ṣāghānī: Abū Ḥāmid Aḥmad ibn Muḥammad al-Ṣāghānī al-Asṭurlābī. In Biographical encyclopedia of astronomers (pp. 1902–1903). Heidelberg: Springer.CrossRefGoogle Scholar

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© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • Boris A. Rosenfeld
    • 1
  1. 1.State CollegePAUSA