In the 4th century CE, the Surya Siddhanta, an astronomical treatise, introduced the concept of a spherical Earth and laid the foundation for time measurement in ancient India. It highlighted Ujjain (referred to by its ancient name, Avanti) and Rohtak (formerly known as Rohitaka) as pivotal locations for the prime meridian or zero longitude, which significantly influenced the region’s time-keeping practices.
Ancient Indian astronomers calculated time starting from sunrise at Ujjain’s prime meridian. They divided the day into precise units, beginning with the prāṇa—the duration of a single breath. Following this, a pala consisted of six prāṇas, a ghalikā was made up of 60 palas, and a nakṣatra ahórātra, or astronomical day, contained 60 ghalikās. This detailed system even defined an astronomical month, the nakṣatra māsa, as comprising 30 days.
According to the Surya Siddhanta, a prāṇa, or one respiratory cycle, was measured as 4 seconds, aligning with modern medical findings of a normal breathing rate at 15 breaths per minute. The text also proposed methods for converting local time to the standard time of Ujjain. Despite these advancements, a unified standard time wasn’t widely adopted until the colonial period, with regions throughout India maintaining their own local times, often guided by the Hindu calendar.
During British Colonial Rule, India saw the introduction of Madras Time by John Goldingham in 1802, which became a reference for railway timings across the country. Significant cities like Bombay and Calcutta established their own time zones, but the quest for a unified Indian Standard Time (IST) prevailed. In 1905, a single time zone for India was officially established, centered on the meridian at 82.5° E longitude east of Allahabad, which brought the country under a uniform time standard (UTC+05:30) from 1 January 1906.
The adoption of IST didn’t erase local time zones overnight. Calcutta and Bombay Time continued until 1948 and 1955, respectively. The period also saw the synchronization of time through telephone systems and, eventually, radio broadcasts by the government. During World War II, IST was temporarily advanced by an hour, a period known as War Time.
After Independence, IST was affirmed as the official time across India, though regional differences lingered briefly in cities like Mumbai and Kolkata. Proposals have emerged, such as in Assam in 2014, to adopt daylight saving time, but no changes have been implemented. The Plantations Labour Act of 1951 allows for local time settings in specific industrial areas, leading to the adoption of a separate time zone in Assam’s tea gardens, known as Chaibagan or Bagan time, which runs an hour ahead of IST. Nevertheless, IST remains the sole official time standard across India.
Which Timezone Is Used in India?
India operates under a single time zone, known as Indian Standard Time (IST), which is UTC+05:30. This standard applies uniformly across the entire country, with no distinctions for different regions or states.
Which Time Zone Passes in India?
The central meridian for India’s standard time zone, IST, passes east of Allahabad at 82.5° E longitude. This meridian was selected to provide a single, unified time standard for the entire country.
What Is UTC Time in India Now?
Indian Standard Time (IST) is set at UTC+05:30. This means India is always five and a half hours ahead of Coordinated Universal Time (UTC).
Which GMT Is Closest to India?
The term “GMT” (Greenwich Mean Time) is often used interchangeably with UTC in casual contexts. Since India operates on UTC+05:30, it aligns closest to GMT+05:30, though this specific designation is not officially used in global time zone standards.
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