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Indian Standard Time

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Location of Mirzapur, and the 82.5°E latitude that is used as the reference longitude for the Indian Standard Time.

Indian Standard Time (IST) is the time observed throughout India with a time offset of UTC+5:30. India does not observe daylight saving time (DST) or other seasonal adjustments, although it was used briefly during the Sino-Indian War (1962), the Indo-Pakistani War of 1965, and the Indo-Pakistani War of 1971. In certain time-zone maps, IST is also designated as E*.[1]

Indian Standard Time is calculated based on the 82.5 °E longitude which passes outside the town of Mirzapur near Allahabad in the state of Uttar Pradesh. The latitude difference between Mirzapur and the Royal Observatory, Greenwich in the UK translates to an exact time difference of 5 hours and 30 minutes. Local time is calculated from a clock tower at the Allahabad Observatory (25°09′N 82°30′E / 25.15°N 82.5°E / 25.15; 82.5) which lies between the two towns.[2].

History

John Goldingham is credited with the establishment of the current fractional time zone (UTC+5:30).

For most of India's history, local time was observed by the ruling kingdoms. Indian kingdoms were known to have precise mathematical models of years and days with the widespread usage of the Hindu calendar. In 1792, the British East India Company established the Madras Observatory in Madras (now Chennai) largely due to the efforts of Michael Topping, a sailor-astronomer. In 1802, John Goldingham, nominated as the first official astronomer of the Company in India, established the longitude of Madras (13°5′24″N 80°18′30″E / 13.09000°N 80.30833°E / 13.09000; 80.30833) being 5 hours and 30 minutes ahead of Greenwich Mean Time as the Standard Time, the first instance of such use. The clock in the observatory was attached to a gun which was fired at 8 pm every day to announce that "all was well" with Indian Standard Time.[3]

Most of the towns in India continued to have their own local time until a few years after the introduction of the railways in the 1850s when the need of a unified time zone became apparent. As headquarters of the two largest Presidencies of British India, local time in Bombay (now Mumbai) and Calcutta (now Kolkata) assumed special importance, with the gradual adoption of these time zones by the nearby provinces and princely states.[4]

IST in relation with the neighbouring countries of South Asia.

In 1884, the International Meridian Conference held at Washington, D.C. in the United States set up uniform time zones across the world. It was decided that India were to have two time zones, with Calcutta using the 90th east meridian and Bombay the 75th east meridian. Calcutta time was set at 5 hours, 30 minutes, and 21 seconds in advance of GMT, while Bombay time was 4 hours and 51 minutes ahead of GMT. [5] However by the late 1880s, many railway companies began to use the Madras time (or Railway time) as an intermediate between the two time zones. Another time zone, the Port Blair mean time was established at Port Blair, the capital of the Andaman and Nicobar Islands in the Bay of Bengal. The time there was set to 49 minutes 51 seconds ahead of Madras time. [6]

British India did not officially adopt the standard time zones, however, until 1905 when the meridian passing east of Allahabad at 82.5 degrees east longitude was picked as the central meridian for India, corresponding to a single time zone for the country at 5 hours and 30 minutes in advance of GMT. This went into force on January 1, 1906 and also applied to Sri Lanka (then Ceylon). However Calcutta time was officially maintained as a separate time zone until 1948.

Bombay time however faced more difficulties in converting to IST. During the same time period in Mumbai, Bal Gangadhar Tilak, a prominent freedom fighter of the Indian independence movement was put on trial in a bomb blast case. With public sentiment against the government, prominent barrister Pherozeshah Mehta fervidly argued against the time change.[7] He managed to stall proceedings in the Bombay Municipal Corporation for a few days by arguing that the government did not take the people into confidence. Faced with rising public resentment over the trial, the government shelved the conversion, and Bombay time was maintained until 1955.[8] After India's independence in 1947, the Indian government established the Indian Standard Time as the official time of India, though Calcutta and Bombay continued to maintain their own local time for the next couple of years. The Central observatory was also moved from Madras to Mirzapur so that it would be as close to UTC +5:30 as possible. Pakistan continued to use the IST for four years before switching to the Pakistan Standard Time (UTC+5) in 1951.

During the Sino-Indian War (1962), the Indo-Pakistani War of 1965, and the Indo-Pakistani War of 1971, daylight saving time was used briefly to reduce civilian energy consumption.[1]

Problems

File:Time-zone-India-Fedora.png
The time zone for India is set to Calcutta shown here in Fedora Core 5.

Though having a unified time zone has its advantages, it also creates problems when the east-west distance is large. With a east-west distance of over 2,000 km (1,200 mi), India is the second largest country after the People's Republic of China to have a single time zone. As a result, the sun rises and sets an hour earlier in eastern India than in the west. Inhabitants of India's north-eastern states have long demanded a separate time zone in order to keep with the early sunrise and avoid the consumption of energy after daylight hours.[2]

During the late 1980s, a team of researchers had suggested a proposal to separate the country into two to three time zones to conserve energy. The two time-zone formula suggested returning to the British-era time zones, while the three time zones would include Bhopal in Madhya Pradesh at the centre of an intermediate time zone. The recommendations however, did not lead to any concrete actions.[2][9]

In 2001 the government of India set up a four-member committee under the Science and Technology Department to examine the need for multiple time zones and usage of daylight saving hours. The committee however, did not recommend any changes.[2]

A error noticed by users of the Linux operating system is the use of Calcutta as the default city for IST while setting the date preferences. This designation should be New Delhi, which hosts the time keeping equipment of the nation.

Time signals

In India today, official time signals are generated by the Time and Frequency Standards Laboratory at the National Physical Laboratory (NPL) based in New Delhi for commercial and official use. The signals are based on the atomic clocks and are tied into the world-wide system of clocks that support the Universal Coordinated Time.

Features of the Time and Frequency Standards Lab include:[10]

  • Four caesium and rubidium atomic clocks
  • HF broadcast service operating at 10 MHz under call sign ATA to synchronise the user clock within a millisecond.
  • INSAT satellite-based standard time and frequency broadcast service which offers IST correct to ±10 microsecond and frequency calibration up to ±10−10.
  • Time and frequency calibrations are made with the help of pico- and nano-seconds time interval, frequency counters, and phase recorders.

As a means of getting the exact time to the masses, many phone companies have special numbers connected to the mirror time servers that allow a caller ascertain the correct time by dialling in.

See also

References

  1. ^ a b "India Time Zones". Retrieved 2006-08-12.
  2. ^ a b c d Sen, Ayanjit (2001-08-21). "India investigates different time zones". BBC News. Retrieved 2006-08-12. {{cite web}}: Check date values in: |date= (help); External link in |work= (help)
  3. ^ "History of Indian Time (IST)". Greenwich Mean Time (GMT). Retrieved 2006-08-13. {{cite web}}: External link in |work= (help)
  4. ^ "Odds and Ends". Indian Railways Fan Club. Retrieved 2006-08-13. {{cite web}}: External link in |work= (help)
  5. ^ "Indian Time Zones (IST)". Project Gutenberg. International Conference Held at Washington for the Purpose of Fixing a Prime Meridian and a Universal Day. October, 1884 Protocols of the Proceedings. Retrieved 2006-08-13. {{cite web}}: External link in |work= (help)
  6. ^ "Note on the earthquake of 31 December 1881, Records of the Geological Survey of India,, XVII(2), 47-53, 1884". Cooperative Institute for Research in Environmental Sciences (CIRES). Retrieved 2006-08-13.
  7. ^ "Bombay time". Mumbai-central.com. 2001-12-08. Retrieved 2006-08-13. {{cite web}}: Check date values in: |date= (help); Cite has empty unknown parameter: |1= (help); External link in |work= (help)
  8. ^ D. Murali (2006-06-23). "Hopeful thinking can get you out of your fear zone". The Hindu Business Line. The Hindu Group. Retrieved 2006-08-13. {{cite web}}: Check date values in: |date= (help); External link in |work= (help)
  9. ^ S. Muthiah (2002-01-07). "A matter of time". The Hindu Business Line. The Hindu Group. Retrieved 2006-08-13. {{cite web}}: Check date values in: |date= (help); External link in |work= (help)
  10. ^ "Indian Time Today (IST)". Greenwich Mean Time (GMT). Retrieved 2006-08-13. {{cite web}}: Cite has empty unknown parameter: |1= (help); External link in |work= (help)
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