Appendix to Ibn Sīnā's Summary of the Almagest; sometimes copied as a separate treatise (e.g. Istanbul, Ayasofya MS 2589, ff. 51b-53b and Istanbul, Ahmet III MS 3303/2, ff. 65b-68a). The latter manuscript is listed by Mat/Ros II, p. 232 (A8) under the titles al-Mukhtaṣar fī ʿilm al-hay’a and al-Falak wa-’l-manāzil, but we do not know if the other listed manuscripts are in fact this appendix. Cf. Sezgin VI, p. 280, n. 2.
Jūzjānī tells us that his master “presented unprecedented material at the end of the Almagest on astronomy” (Gohlman, pp. 64-5). This turns out to be somewhat of an exaggeration since most of the matters discussed had been dealt with by previous Islamic astronomers who had criticized or updated Ptolemy and offered some correctives. Among the topics are: (1) the dynamics of celestial motion, i.e. how one orb can move another; (2) a mathematical examination of the implications of the theoretical construction of Ibrāhīm ibn Sinān (d. 946), who is unnamed, that would account for the discrepancies between the precessional rates and obliquities of Ptolemy and those of ninth-century Islamic astronomers (Ragep [1993], 2: 394-408). It is noteworthy that Ibn Sīnā gives his own observed value of the obliquity as 23;33,30°; (3) the motion of the solar apogee, taken to be fixed by Ptolemy, and a proposal to explain its motion; and (4) the problem of latitude brought about by the epicycle poles. This seems somehow related to the theory put forth by his contemporary Ibn al-Haytham (Ragep [1993], 2: 450-2).