Barahmihir (499?-587?) ancient Indian astronomer and poet. Born at Abantinagar in India, Barahmihir was one of the nine jewels of the royal court of Vikramaditya. Besides astronomy, he was an adept in meteorology, engineering and architecture. It is said that Barahmihir was not a single person, 'Barah' was the name of the father and his son was 'Mihir'. In 550, Barahmihir wrote his famous Panchasiddhantika which contains a rich discussion on astronomy and astrology. This masterpiece comprises five parts or Siddhanta. These are Suryasiddhanta, Romaksiddhanta, Poulishsiddhanta, Paitamahasiddhanta and Bashisthasiddhanta. He is also the author of the Brihatsanghita, written in verse, in which he gives a description of various gems, a geographical description of the Indian subcontinent and an account of the rotation of the sun and the moon and their effects.

In his book, Barahmihir highlights the importance of astronomy in meteorology, architecture and engineering works and also describes the making process of a substance 'Brojolep' similar to modern cement. In ancient India big buildings were built using Brojolep. Barahmihir was the reformer of the Indian calendar and introduced the tradition of counting Baishakh as the first month of the bangla calendar. Previously Chaitra and Baishakh were counted as months under Hemanta (late autumn). The present Bangla calendar is after the system introduced by Barahmihir. He also possessed a clear conception of the size and shape of the earth. The actual date of Barahmihir's death is not known and according to one group of historians he died in 587 AD while another group believes that he died in 578 AD. [Md Mahbub Murshed]