John Abramios astrologer and astronomer; fl. Constantinople and Mytilene, 1370–90. Abramios (᾽Αβράμιος) practiced magic and cast Horoscopes on behalf of Andronikos IV and his son John VII, in their quarrels with John V and Manuel II. His most important role was as the editor of texts of classical astrology, the author of treatises on astronomy (opposed to the Ptolemaic tradition of Theodore Metochites, Nikephoros Gregoras, and Isaac Argyros, Abramios followed the Islamic tradition of Gregory Chioniades, George Chrysokokkes, and Theodore Meliteniotes), and as the founder of a school in which these activities were continued until ca.1410. His successors were Eleutherios Zebelenos, also known as Eleutherios Elias (born 1343), and Dionysios.
A number of MSS of astronomical, astrological, medical, magical, and rhetorical content produced by Abramios and his school survive. They produced editions of Ptolemy, pseudo-Ptolemy, Hephaistion of Thebes, Olympiodoros of Alexandria, and Rhetorios of Egypt. These editions are characterized by changes in both the grammar and the order of the presentation of the technical material of the original texts, and by the insertion of extraneous material into them. These MSS also contain some examples of Greek translations of Arabic astrological texts, notably the Mysteries of Abū Maʿshar and the Introduction of Aḥmad the Persian.
In 1376 Abramios wrote a treatise on the conjunctions and oppositions of the sun and moon based on the New Tables of Isaac Argyros, but criticized his source because he followed Ptolemy rather than the Persian Tables popularized by Chrysokokkes. This led to the computation by both sets of tables of the dates, and sometimes the details, of 39 lunar and solar eclipses between 1376 and 1408, and an inept attempt to prove that the Islamic value for the rate of precession of the equinoxes is superior to that of Ptolemy.