Indian Standard Time(IST) is the time observed throughout India, with a time offset of UTC+05:30. India does not observe daylight saving time(DST) or other seasonal adjustments. In military and aviation time IST is designated E* (“Echo-Star”).
Indian Standard Time is calculated on the basis of 82.5′ E longitude, in Mirzapur , Uttar Pradesh, which is nearly on the corresponding longitude reference line.
History of India’s Time Zone
Time zones were officially established in India in 1884, during British rule. Two time zones were used — Bombay Time and Calcutta Time — due to the importance of these cities as commercial and economic centers. In addition, Madras Time (set up by astronomer John Goldingham in 1802) was followed by many railway companies.
IST was introduced on January 1,1906. However, Bombay Time and Calcutta Time continued to be maintained as separate time zones until 1955 and 1948 respectfully, after India’s Independence.
After independence in 1947, the Indian government established IST as the official time for the whole country, although Kolkata and Mumbai retained their own local time (known as Calcutta Time and Bombay Time) until 1948 and 1955, respectively.The Central observatory was moved from Chennai to a location at Shankargarh Fort in Allahabad district, so that it would be as close to UTC+05:30 as possible.
Although India currently doesn’t observe Daylight Saving Time, it did briefly exist during the Sino-Indian War in 1962 and the India-Pakistan Wars in 1965 and 1971, in order to reduce civilian energy consumption.
Daylight Saving Time (DST) was used briefly during the China–Indian War of 1962 and the Indo–Pakistani Wars of 1965 and 1971.
Criticism and proposals
The country’s east–west distance of more than 2,933 kilometres covers over 29 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on India’s eastern border than in the Rann of Kutch in the far west. Inhabitants of the northeastern states have to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours.
In the late 1980s, a team of researchers proposed separating the country into two or three time zones to conserve energy. The binary system that they suggested involved a return to British–era time zones; the recommendations were not adopted.
In 2001, the government established a four–member committee under the Ministry of Science and Technology to examine the need for multiple time zones and daylight saving. The findings of the committee, which were presented to Parliament in 2004 by the Minister for Science and Technology, Kapil Sibal, did not recommend changes to the unified system, stating that “the prime meridian was chosen with reference to a central station, and that the expanse of the Indian State was not large.”
Though the government has consistently refused to split the country into multiple time zones, provisions in labour laws such as the Plantations Labour Act, 1951 allow the Central and State governments to define and set the local time for a particular industrial area. In Assam, tea gardens follow a separate time zone, known as the Chaibagaan or Bagan time (‘Tea Garden Time’), which is one hour ahead of IST. Still Indian Standard Time remains the only officially used time.
The filmmaker Jahnu Barua has been campaigning for a separate time zone (daylight saving time) for the past 25 years. In 2010, he suggested creating a separate time zone for the Development of Northeastern Region.In 2014, Chief Minister of Assam Tarun Gogoi started campaigning for another time zone for Assam and other northeastern states of India.However, the proposal would need to be cleared by the Central Government of India.
In June 2017, Department of Science and Technology (DST) indicated that they are once again studying feasibility of two time-zones for India. Proposals for creating an additional Eastern India Time (EIT at UTC+06:00, shifting default IST to UTC+05:00 and Daylight saving (Indian Daylight Time for IST and Eastern India Daylight Time for EIT) starting on 14 April (Ambedkar Jayanti) and ending on 2 October (Gandhi Jayanti) was submitted to DST for consideration.
Official time signals are generated by the Time and Frequency Standards Laboratory at the National Physical Laboratory in New Delhi, for both commercial and official use. The signals are based on atomic clocks and are synchronised with the worldwide system of clocks that support the Coordinated Universal Time.
Features of the Time and Frequency Standards Laboratory include:
- High frequency broadcast service operating at 10 MHz under call sign ATAto synchronise the user clock within a millisecond;
- Indian National Satellite System satellite-based standard time and frequency broadcast service, which offers IST correct to ±10 microsecond and frequency calibration of up to ±10−10; and
- Time and frequency calibrations made with the help of pico- and nanoseconds time interval frequency counters and phase recorders.
- IST is taken as the standard time as it passes through almost the centre of India. To communicate the exact time to the people, the exact time is broadcast over the national All India Radio and Doordarshan television network. Telephone companies have dedicated phone numbers connected to mirror time servers that also relay the precise time. Another increasingly popular means of obtaining the time is through Global Positioning System(GPS) receivers.
UTC and IST and Time Differential
India Standard Time (IST) is 5:30 hours ahead of Coordinated Universal Time (UTC). This time zone is in use during standard time in: Asia. India Standard Time is a half-hour time zone. Its local time differs by 30 minutes instead of the normal whole hour.In case of India the difference is 7 and half degree because of 30 minutes differential.If each time zone were 1 hour apart, there would be 24 in the world. However, the actual borders on the time zone map have been drawn to match up with both internal and international borders, and rarely match up exactly with the 15-degree longitudes. .Also, the International Date Line (IDL), creates 3 time zones and several time zones are only 30 and 45 minutes apart. This makes the total number of time zones worldwide much higher.
Email Time Zone Indicator: +0530
An email sent from someone in the India Standard Time (IST) time zone will have the time zone listed as “+0530” in the headers of the email. (However, “+0530” does not have to be in India Standard Time, as other time zones could have the same UTC offset).
Link(s) and Source(s):
अक्षांश, देशांतर, ताप कटिबन्ध और समय निर्धारण का तरीका