Intro page | How to Read the Tables | The Olympiad System | Sources | Analysis
These pages give access to conversion tables in Excel format, with copies in HTML format and in CSV format, useful for determining the Julian equivalent of years dated according to Olympiads during the Ptolemaic era. This system was used by Greek historians to provide a common frame of reference to reconcile historical dates given in many different local calendars. It is particularly important for interpreting the regnal years attributed to the Ptolemies by Porphyry, as transmitted through the works of Eusebius.
The conversion tables for the Olympiads are straightforward. The columns give the following information:
The first column gives the Julian year in which the corresponding Olympic year starts. Since Olympic years typically run from summer to summer, the first part of the named Julian year actually corresponds to the previous Olympic year
The second column gives the Olympic year that starts in the named Julian year. Since Olympic years typically rom summer to summer, the last part of the named Olympic year actually corresponds to the next Julian year.
Olympic years are numbered in the form <Olympiad>.<offset>, where the <Olympiad> identifies the number of an Olympic Games, and the <offset> identifies a year of the four-year Olympic cycle, numbered from 1 to 4. <offset> = 1 is a year in which the Olympic festival was held. These years are bolded. Ol. 1.1 = 776/5 B.C.
The third column gives the date of the second full moon after the summer solstice in the named Julian year. In Olympic years, this is the date of the festival that closed the Games, and so can be taken to mark the nominal start of the corresponding Olympic year.
The next three columns give the regnal year(s) of the Ptolemaic kings corresponding to the named Olympic year, in red, according to Porphyry's system. If Porphyry recognises more than one regnal year for an Olympic year, all are given. If the regnal year is only nominal, i.e. not actually used, but is needed to indicate the progress of a series for some reason, it is given in normal case.
The next column identifies the kings whose regnal years are given in the preceding columns. A change in ruler are marked by diagonal lines corresponding to the year in which the change took place. Rulers reigning jointly, or other arrangements that do not involve a change of ruler (notably Ptolemy I's ascent from satrap to king) are demarcated by dotted lines rather than solid ones.
The final columns give the same information for the system of Eusebius, as reported by Jerome.
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