Renæssanceforum 3 • 2007

Fritz S. Pedersen
Astronomical tables for Pisa in ms. København K.B., GkS 277, fol.

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A set of astronomical tables for Pisa, composed about AD 1143 by Abraham b. Ezra, has so far been known from five manuscripts. This paper presents a sixth one, from the mid-thirteenth century, noticed in 1994 by the late Wilbur Knorr in the Royal Library, Copenhagen, and first identified on the present occasion. The mean motion tables are likely to have ended in 1209 originally, and they have had various continuations in the different witnesses. The Copenhagen manuscript, too, has been continued, no doubt by two different persons, one of whom seems to have wanted to adapt the tables for use in Paris, whereas the other was a particularly inept calculator. This seems to be quite a typical state of affairs when complicated arrays of numerals were to be updated.