A couple of months ago I published “Alexandria and the Moon”, a monograph on the lunar Macedonian calendar, as Studia Hellenistica 52. Although it is mostly concerned with Ptolemaic Egypt, I added an appendix on intercalation outside Egypt. Inter alia, this included a calendrical analysis of the dates in two letters of Antiochus III, which concluded that the two years involved – SEM 103 = 210/9 and 119 = 194/3 – did not conform to the standard model of the Seleucid Macedonian calendar propounded by Jotham Johnson in 1932, and that these years were most probably ordinary years.
Shortly after publication, Farhad Assar pointed out an elementary arithmetic blunder in this discussion. When this is corrected, SEM 103 was certainly, and SEM 119 probably, intercalary, following Johnson’s model, but the intercalary month in these years was after Dystros, not Xandikos, i.e. the calendar of Antiochus III appears to be the same as the Parthian Macedonian calendar documented in the coinage of Seleucia-on-Tigris 150 years later, and at Dura Europos and Kushan Gandhara.
For this interested I have uploaded an Addenda & Corrigenda note to Academia.edu which goes into detail and outlines the implications of this correction: http://independent.academia.edu/ChrisBennett/Papers/1194863/Alexandria_and_the_Moon_Addenda_et_Corrigenda
[Non-text portions of this message have been removed]