has his researches been published ?
Yes, "Almagest".
Ptolemy
Ptolemy's "Almagest" is the only surviving comprehensive ancient treatise on astronomy. 
what is serpens? A constellation of the northern hemisphere. who discovered it? Ptolemy. who was he? A mathematician, astronomer and astrologer. what kind of researches had he carried out? He estimated the Sun was at an average distance of 1,210 Earth radii.
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Ptolemy [SEP] Astronomy
Ptolemy's "Almagest" is the only surviving comprehensive ancient treatise on astronomy. Babylonian astronomers had developed arithmetical techniques for calculating astronomical phenomena; Greek astronomers such as Hipparchus had produced geometric models for calculating celestial motions. Ptolemy, however, claimed to have derived his geometrical models from selected astronomical observations by his predecessors spanning more than 800 years, though astronomers have for centuries suspected that his models' parameters were adopted independently of observations. Ptolemy presented his astronomical models in convenient tables, which could be used to compute the future or past position of the planets. The "Almagest" also contains a star catalogue, which is a version of a catalogue created by Hipparchus.