On the recommendations of the Calendar Reforms Committee under the chairmanship of the late Professor Meghnad Saha, a Nautical Almanac Unit was established in IMD at Calcutta in 1955 to meet the national needs for astronomical data for scientific and general purposes. It was further augmented in 1979 and renamed as Positional Astronomy Centre (PAC). It now functions at Calcutta under the direct control of the Director General of Meteorology who is advised by a Standing Advisory Committee.
 

Publications:

PAC compiles and publishes the following important annual publications:

• Indian Astronomical Ephemeris
• Tables of Sunrise & Sunset and Moonrise & Moonset.
• Rashtriya Panchang in 14 languages viz.
  ( Hindi, English, Sanskrit, Urdu, Assamese, Bengali, Gujarati,
  Kannada, Malayalam, Marathi, Oriya, Punjabi, Tamil and Telugu ).

The Indian Astronomical Ephemeris contains over 600 pages of astronomical data on the position of Sun, Moon, Planets, and Bright Stars and a section on the National Calendar of India (Saka Calendar) with the timings of Tithis, Nakshatras etc. and the festival dates. The publication is now in its 42nd year. Rashtriya Panchang is a popular publication brought out with the aim of providing a standard unified calendar for the whole country and promoting a scientific basis for Panchang calculation. PAC brought out an English translation of Bhartiya Jyotish Shastra in two parts from the original Marathi version by late Shri S.B. Dixit, which is a pioneering work on the history of ancient and medieval India astronomy.
 

Data Services:

The Centre meets the data requirements of a large number of users. Lunar data for prediction of tides are computed for the Survey of India and data of the Sun's daily path are useful to civil engineers, architects and telecommunications engineers. PAC provides data for determining the dates of festivals of all communities in India in advance for holiday declaration by the Government, tourist promotion abroad and for use of Panchang Makers.
 

Popularisation of Astronomy:

The Centre contributes to a great extent in popularising astronomy through its monthly Star Chart and Astronomical Bulletins published in 40 newspaper editions throughout the country. It organises popular lectures and night sky viewing for public through telescopes and by publishes popular articles on different topics of astronomy in newspapers and magazines.
 

Total Solar Eclipse Studies:

PAC organises special expeditions and experiments for astronomical and meteorological observations during Total Solar Eclipse events. It also publishes advance information related to both solar and lunar eclipses, including climatological data which are important for eclipse viewing purposes.