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Synopsis The Indian Astronomical Ephemeris is published annually by the India Meteorological Department (IMD) for providing data to astronomers.  The speciality of this publication is that it contains calendric information which caters to the requirement of the country’s panchang makers and other users.  It thus has great civil and cultural significance.  This has been the mandate given to the Positional Astronomy Centre at Kolkata by the Govt. of India.

The calculations of the Indian Calendar portion, such as tithi, nakshatra etc. are given in Indian Standard time (IST) and covers an extended period upto 21st March 2021 which is the end of the year 1933 Saka Era of the Indian National Calendar.  A separate note has also been given to explain the terminology and the basis of different calculations relating to the Indian Calendar.

In accordance with resolutions adopted by the International Astronomical Union (IAU) at its meetings held in 1976 and 1979 relating to time, reference frame and astronomical constants, the epoch of the standard reference system in this publication is J 2000.0 and the argument of the ephemeredes is Terrestrial Time (TT).  A complete list of changes introduced, is given immediately after the preface.  Resolutions of the IAU recommending the above changes in a consistent manner, including a list of new IAU constants are given in Part VI – Indian Calendar and Explanation.