How Indian Standard Time was introduced in the country: On 1st September 1947, the IST (Indian Standard Time) phenomenon was introduced to the country as the official time. Throughout India, IST is observed, with a time offset of UTC + 5.30, which means India is 5.30 hours ahead of Greenwich Mean Time (GMT).
Like other countries, India does not follow Daylight Saving Time. 82.5 degrees East longitude from a clock tower in Mirzapur near Allahabad is the basis for IST calculation. Because it is nearer to the corresponding longitude reference line.
Surya Siddhanta
In India, the book ‘Surya Siddanta’ talked about the standard time in the 4th century CE. In the old times, a day in India starts with sunrise at the Prime Meridian, Ujjain and it had been then divided into smaller time units.
India first received a cohesive timezone in 2802, after the establishment of the longitude of Chennai as 13°5′24″N, 80°18′30″E by the British astronomer John Goldingham. This was five hours and thirty minutes ahead of GMT. After this advancement, India’s day began at midnight 12, instead of the initial practice, sunrise.
Despite Goldingham’s advancement, most cities and towns continued to rely on their own local measurement system until the estan=blishment of the Railway system in the 1850s.
In the year 1884, Kolkata and Mumbai became the major centers for the British and they were established as time zones. Mumbai was set at 4 hours and 51 minutes ahead of GMT and Kolkata was at 5 hours and 30 minutes ahead. In the year 1905, the meridian which was passing east of Allahabad was announced as a standard time zone for the country and in 1947, it was declared as IST.
