Calendar conversion and astronomical tables
Raymond Mercier
Cambs, England


Email Address:





Now in ZDMG vol 171 (2021) 425-458

 ‘The epoch year of the Gaṅga Era’

Abstract   The problem of determining the epoch date of the Ganga Era is approached through a comprehensive study of the twelve eclipses, solar and lunar, that are dated in that era. The result is that the epoch year is AD 607, or Śaka 529. Detailed results for all the eclipses are given, including maps showing the regions in India where the solar eclipses are visible. The Harsha Era has the same epoch year, and the relation with the Ganga Era is discussed.

There is no pdf. If you wish to have an offprint please contact me by email.



Just appeared :

‘On the Originality of Indian Mathematical Astronomy’, in The Interactions of Ancient Astral Science, edited by David Brown, Hempen Verlag 2018.


Recent publications : 

Conformément aux observations d’Hipparque : le Papyrus Fouad inv, 267 A,

by Jean-Luc Fournet, Anne Tihon, Annex by Raymond Mercier, Leuven : Peeters, 2014.


ʽAstronomical tables of Abraham bar Ḥiyyaʼ,

in Time Astronomy and Calendars in the Jewish Tradition, edited by Sasha Stern and Charles Burnett, Brill 2014.


Blog on the astronomy of Jai Singh as a follow-up to the Moghul Exhibition at the British Library (April 2013)


An essay on Indian astronomy, ‘The reality of Indian astronomy’, details here.

Critical edition of the Handy Tables of Ptolemy.


Older articles, already published, are also available here as pdf files.


My site offers a number of programs created in the course of my work in the history of medieval and oriental astronomy.

    The main programs are
    general calendar conversion program.
    graphical and numerical analysis of the parameters of historical astronomical canons
  listing of star coordinates based on the Bright Star List

Fontlist 5 and Fontlist 6 were developed in order to make it easier to handle a variety of fonts when using MS Word, amd now Word 2007.
Both are fully unicode compliant, listing the fontname in appropriate CJK characters. It will open any file, even when the filename consists of non-ascii characters.

Hanfind is designed to exploit the database UniHan.txt provided by Unicode. Hanfind provides, among other features, a list (sorted by tones) of all the Chinese characters for a given Pinyin reading.

Unicode Search is for those people who have hundreds of fonts on the disk, and need to know which will cover a given set of Unicode blocks. For example if you need to type Classical Greek, you need the blocks "Greek" and "Greek extended". If you want to transcribe oriental languages, you need besides the usual Latin blocks, also "Latin extended Additional". Do you really know which fonts you have for that ? Unicode Search has the answer !


Interested in the Royal Wedding ? Have fun interpreting the Horoscope for the day, as calculated by Kairos
Royal Wedding Horoscope

Local Scenes from Cambridgeshire : Ely, St.Ives and Hemmingford Grey