Examining the continuity of the ancient calendars of Cyprus, especially with regard to the month of Aphrodisios and its placement in springtime.

Various proposals of how the Arabian Calendar was before Islam are compared and evaluated including, the present Islamic calendar, Pre-Islamic intercalation, the algorithm of intercalation, the start of the year and when the system was abolished.

The name Hemerologia identifies a set of comparative calendar tables preserved in early medieval Greek manuscripts which comprise the Julian calendar and a number of local calendars of the provinces and cities of the eastern half of the Roman Empire. I present some preliminary results of my on-going research, which consists in a re-assessment of the information provided by the manuscripts by taking into account newly discovered epigraphic and documentary evidence since the only edition of this work, published over a century ago.

Rabbinic sources of all periods and times are deeply committed to a human-regulated luni-solar calendar, however small number of late tannaitic sources show a commitment to the 365-day year. I shall examine the background and the message of two statements on the matter and establish their relation with other rabbinic statements on the calendar.

It will be demonstrated that the data in the Aramaic calendrical scroll from Qumran, 4Q209, represents an ideal year in the 19-year cycle, known as the Metonic Cycle.

Sacha Stern introduces and sums up the results of a 5-year research project at UCL, funded by the European Research Council (ERC), on ‘Calendars in late Antiquity and the Middle Ages: Standardization and Fixation’. The overarching question of the project: how Roman, Christian, Jewish, and Islamic calendars evolved, in late Antiquity and the Middle Ages, towards ever increasing standardization and fixation is discussed.

In the Jewish year 5070 Isaac Israeli ben Joseph the Younger composed an extensive and highly scientific treatise on the Jewish calendar. The first of the five books of Yesod Olam is dedicated mainly to Euclidean geometry and spherical trigonometry. Presented here is a discussion of the mathematical materials and their direct or indirect relevance to the Jewish calendar and in particular, the non-traditional partial transmission of Euclid’s Elements.

Under the Saljuqid ruler Jalal al-Dawla Malik-Shah (died 1092 C.E.) a new calendar with the era 15 March 1079 was introduced. Up to this time, the old Persian calendar with a fixed year of 365 days was still in use, and the first regnal year of Yazdagird III (632 C.E.) served as its epoch. Explored here is the relationship of the two calendars, their use and their symbolic significance in the late Saljuq epoch and beyond.

The Chronology of al-Biruni is a classic Arabic book on calendars and chronology written in the year 1000 CE. Presented here are some results of work on a new edition and translation including an overview of its contents and an analysis of some of the sections that are either missing in the printed edition, or that have not been understood until now.

The Gregorian calendar reform of 1582 has its intellectual roots in the European Middle Ages, when the reckoning of time by means of calendrical cycles was a topic of central importance to education and learned culture. This talk will focus on several previously unknown source texts and the way they shed new light on the various factors that fostered or inhibited the calendar reform debate in the later medieval period, from c. 1200 to 1500.