Persian Planispheric Astrolabe

This astrolabe was made in the Persian city of Isfahan in about 1715. Isfahan is now in Iran. The object includes a body with throne, a handle that holds a ring for suspending the device, and five plates. One side of one plate has quarter horizons for every three degrees of latitude between twelve degrees and sixty-six degrees. The remaining faces of the plates show a stereographic projection of circles on the celestial sphere for latitudes from twenty-nine degrees to forty degrees. The astrolabe also has a rete or star map, an alidade on the back for sighting stars, a pin that passes through the center, and a wedge that holds the pin in place.

The upper left quadrant of the back of the astrolabe contains a grid of lines. Horizontal lines represents sines of angles, vertical ones cosines. The rectangular box below the center of the back includes a scales of tangents and cotangents of angles.

For a detailed description of the instrument, see Gibbs and Saliba.

The maker, ‘Abd al-A’imma, is well known in the history of Persian astrolabe making, although little biographical information survives. The Smithsonian acquired the instrument from the collection of Samuel V. Hoffman in 1959. It is number CCA40 on the international computerized checklist of astrolabes.

Compare 333589, 336114, and 316761 which are all by the same maker.

References:

For a detailed description of this object, see Sharon Gibbs with George Saliba, Planispheric Astrolabes from the National Museum of American History, Washington, D.C.: Smithsonian Institution Press, 1984, pp. 74-77. The object is referred to in the catalog as CCA No. 40.

Another astrolabe associated with the maker is described on

Astrolabe Catalog of the Oxford Museum of the History of Science, at www.mhs.ox.ac.uk, accessed March 2, 2016.

Currently not on view