Al-Battani (d 929) - includes timing of the new moons, calculation of the length of the solar and sideral year, the prediction of eclipses and the phenomenon of parallax.'
Al-Battani also popularized if not discovered the first notions of trigonometrical ratios used today and made serious emendations to Ptolemy.
Al-Sufi (903-986) - made several observations on the obliquity of the ecliptic and the motion of the sun (or the length of the solar year.)He also made observations and descriptions of the stars, setting out his results constellation by constellation, discussing the stars positions, their magnitudes and their colour, and for each constellation providing two drawings from the outside of a celestial globe, and from the inside. Al-Sufi also wrote on the astrolabe and its thousand or so uses.
Al-Biruni (973-1050) - claimed that the earth rotated around its own axis. He calculated the earth circumference, and fixed scientifically the direction of Makkah (Mecca) from any point of the globe. Al-Biruni wrote in total 150 works, including 35 treatises on pure astronomy, of which only six have survived.
Ibn Yunus (d 1009) - made observations for nearly thirty years (977-1003) using amongst others a large astrolabe of nearly 1.4 m in diameter, determining more than 10,000 entries of the sun's position throughout the years.
Al-Farghani - was one of Caliph Al-Mamun's astronomers. He wrote on the astrolabe, explaining the mathematical theory behind the instrument and correcting faulty geometrical constructions of the central disc, that were current then. His most famous book Kitab fi Harakat Al-Samawiyah wa Jaamai Ilm al-Nujum on cosmography contains thirty chapters including a description of the inhabited part of the earth, its size, the distances of the heavenly bodies from the earth and their sizes, as well as other phenomena.
Al-Zarqali (Arzachel) - (1029-1087) prepared the Toledan Tables and was also a renowned instrument maker who constructed a more sophisticated astrolabe: a safiha, accompanied by a treatise.
Jabir Ibn Aflah - (d. 1145) was the first to design a portable celestial sphere to measure and explain the movements of celestial objects. Jabir is specially noted for his work on spherical trigonometry. Al-Bitruji's work 'Kitab-al-Hay'ah' was translated by the Sicilian based Michael Scot, and bore considerable influence thereafter.