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Revision as of 11:17, 4 April 2007 editRettetast (talk | contribs)Extended confirmed users158,862 editsm Reverted 1 edit by 59.91.243.117 to last revision by Borgx. using TW← Previous edit Revision as of 20:10, 6 April 2007 edit undoTobias Conradi (talk | contribs)37,615 edits The tz zone identifier for all India is Asia/Calcutta.Next edit →
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Time in India is nowadays represented by the ] (IST, ]). Some older time zones were ] (UTC+4:51), ] (UTC+5:30:21), ]. The ] identifier for all India is Asia/Calcutta.
⚫ ] and the 82.5° E longitude that is used as the reference longitude for Indian Standard Time]]


⚫ '''Indian Standard Time''' ('''IST''') is the ] observed throughout ], with a ] of ]. India does not observe ], (DST) or other seasonal adjustments, although DST was used briefly during the ] and the ] and ].<ref name="timez">{{cite web | url =http://wwp.india-time.com/indian-time-zones.htm | title =India Time Zones | accessdate =2006-11-25| work=}} </ref> In military and aviation time, IST is designated '''E*''' ("Echo-Star").<ref>{{cite web | url = http://wwp.greenwichmeantime.com/info/timezone.htm
⚫ | title = Military and Civilian Time Designations | accessdate =2006-12-02| work=}} </ref>


⚫ Indian Standard Time is calculated on the basis of 82.5° E ], which is just west of the town of ], near ] in the state of ]. The longitude difference between Mirzapur and the ]'s ] at ] translates to an exact time difference of 5 hours 30 minutes. Local time is calculated from a ] at the ] ({{coor d|25.15|N|82.5|E|}}) though the official time-keeping devices are entrusted to the ], in ].<ref name="bbc">{{cite web | url=http://news.bbc.co.uk/2/hi/south_asia/1501252.stm |title=India investigates different time zones|accessdate=2006-11-25 |last=Sen |first=Ayanjit |date=] |work=}}</ref>


==History== ==History==
Line 30: Line 27:
During the ] and the ] and ], daylight saving was briefly used to reduce civilian energy consumption.<ref name="timez"/> During the ] and the ] and ], daylight saving was briefly used to reduce civilian energy consumption.<ref name="timez"/>


==Indian Standard Time==
⚫ ==Problems==
⚫ ] and the 82.5°&nbsp;E longitude that is used as the reference longitude for Indian Standard Time]]

⚫ Indian Standard Time ('''IST''') is the ] observed throughout ], with a ] of ]. India does not observe ], (DST) or other seasonal adjustments, although DST was used briefly during the ] and the ] and ].<ref name="timez">{{cite web | url =http://wwp.india-time.com/indian-time-zones.htm | title =India Time Zones | accessdate =2006-11-25| work=}} </ref> In military and aviation time, IST is designated '''E*''' ("Echo-Star").<ref>{{cite web | url = http://wwp.greenwichmeantime.com/info/timezone.htm
⚫ | title = Military and Civilian Time Designations | accessdate =2006-12-02| work=}} </ref>

⚫ Indian Standard Time is calculated on the basis of 82.5° E ], which is just west of the town of ], near ] in the state of ]. The longitude difference between Mirzapur and the ]'s ] at ] translates to an exact time difference of 5 hours 30 minutes. Local time is calculated from a ] at the ] ({{coor d|25.15|N|82.5|E|}}) though the official time-keeping devices are entrusted to the ], in ].<ref name="bbc">{{cite web | url=http://news.bbc.co.uk/2/hi/south_asia/1501252.stm |title=India investigates different time zones|accessdate=2006-11-25 |last=Sen |first=Ayanjit |date=] |work=}}</ref>

⚫ ===Problems===
A single, large time zone has been shown to cost more, and requires rescheduling of events to make them compatible with the rest of the zone or with the day's cycle. The country's east–west distance of more than 2,000&nbsp;] (1,200&nbsp;]) covers over 28 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on India's eastern border than in the ] in the far west. Inhabitants of the ] have long demanded a separate time zone to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours.<ref name="bbc"/> A single, large time zone has been shown to cost more, and requires rescheduling of events to make them compatible with the rest of the zone or with the day's cycle. The country's east–west distance of more than 2,000&nbsp;] (1,200&nbsp;]) covers over 28 degrees of longitude, resulting in the sun rising and setting almost two hours earlier on India's eastern border than in the ] in the far west. Inhabitants of the ] have long demanded a separate time zone to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours.<ref name="bbc"/>


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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'' do allow the Central and State governments to define and set the local time for a particular industrial area.<ref>{{cite web|url=http://nrcw.nic.in/shared/sublinkimages/19.htm |title=A matter of time |accessdate=2006-11-25 |work=National Resource Centre for Women}}</ref> 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'' do allow the Central and State governments to define and set the local time for a particular industrial area.<ref>{{cite web|url=http://nrcw.nic.in/shared/sublinkimages/19.htm |title=A matter of time |accessdate=2006-11-25 |work=National Resource Centre for Women}}</ref>


==Time signals== ===Time signals===
Official time signals are generated by the ] at the ] in ], for both commercial and official use. The signals are based on ]s and are synchronised with the worldwide system of clocks that support the ]. Official time signals are generated by the ] at the ] in ], for both commercial and official use. The signals are based on ]s and are synchronised with the worldwide system of clocks that support the ].


Revision as of 20:10, 6 April 2007

Time in India is nowadays represented by the Indian Standard Time (IST, UTC+5:30). Some older time zones were Bombay time (UTC+4:51), Calcutta time (UTC+5:30:21), Port Blair mean time. The tz zone identifier for all India is Asia/Calcutta.


History

One of the earliest descriptions of standard time in India appeared in the 4th century CE astronomical treatise Surya Siddhanta. Postulating a spherical earth, the book defined the prime meridian, or zero longitude, as passing through Avanti, the ancient name for the historic city of Ujjain (23°10′58″N 75°46′38″E / 23.18278°N 75.77722°E / 23.18278; 75.77722), and Rohitaka, the ancient name for Rohtak (28°54′N 76°38′E / 28.900°N 76.633°E / 28.900; 76.633), a city near the historic battle-field of Kurukshetra.

Situated upon the line which passes through the haunt of the demons (equator and 76° E) and the mountain which is the seat of the gods (the North Pole), are Rohitaka and Avanti ...

The day used by ancient Indian astronomers began at sunrise at the prime meridian of Ujjain, and was divided into smaller time units in the following manner:

Time that is measurable is that which is in common use, beginning with the prāṇa (or, the time span of one breath). The pala contains six prāṇas. The ghalikā is 60 palas, and the nakṣatra ahórātra, or astronomical day, contains 60 ghalikās. A nakṣatra māsa, or astronomical month, consists of 30 days.

Taking a day to be 24 hours, the smallest time unit, prāṇa, or one respiratory cycle, equals 4 seconds, a value consistent with the normal breathing frequency of 15 breaths/min used in modern medical research. The Surya Siddhanta also described a method of converting local time to the standard time of Ujjain. Despite these early advances, standard time was not widely used outside astronomy. For most of India's history, ruling kingdoms kept their own local time, typically using the Hindu calendar in both lunar and solar units. For example, the Jantar Mantar observatory built by Maharaja Sawai Jai Singh in Jaipur in 1733 contains large sundials, up to 90 ft (27 m) high, which were used to accurately determine the local time.

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

In 1792, the British East India Company established the Madras Observatory in Chennai (then Madras), largely due to the efforts of the British sailor–astronomer Michael Topping. In 1802, John Goldingham, appointed 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) as 5 hours 30 minutes ahead of Greenwich Mean Time as the local standard time. This marked the first use of the current time zone, and departure from the earlier standard of the day beginning at sunrise; now it started at midnight. The clock in the observatory was attached to a gun that was fired at 8 p.m. daily to announce that "all was well" with IST. Time-keeping support for shipping activities in Bombay Harbour was provided by the Colaba Observatory in Bombay, which was established in 1826.

Most towns in India retained their own local time until a few years after the introduction of the railways in the 1850s, when the need for a unified time zone became apparent. Local time in Mumbai (then Bombay) and Kolkata (then Calcutta), as headquarters of the two largest Presidencies of British India, assumed special importance, and was gradually adopted by the nearby provinces and princely states. In the 19th century, clocks were kept in synchronisation through by telegraph – for example the railways synchronised their clocks thorough a time signal that was sent from the head office or the regional headquarters at a specified time every day.

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

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

IST in relation with the bordering nations

In 1925, time synchronisation began to be relayed through omnibus telephone systems and control circuits to organisations that needed to know the precise time. This continued until the 1940s, when time signals began to be broadcast using the radio by the government.

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 for a few more years. The Central observatory was moved from Chennai to a location near Mirzapur, so that it would be as close to UTC +5:30 as possible.

During the Sino–Indian War of 1962 and the Indo–Pakistani Wars of 1965 and 1971, daylight saving was briefly used to reduce civilian energy consumption.

Indian Standard Time

Location of Mirzapur and the 82.5° E longitude that is used as the reference longitude for 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 DST was used briefly during the Sino–Indian War of 1962 and the Indo–Pakistani Wars of 1965 and 1971. In military and aviation time, IST is designated E* ("Echo-Star").

Indian Standard Time is calculated on the basis of 82.5° E longitude, which is just west of the town of Mirzapur, near Allahabad in the state of Uttar Pradesh. The longitude difference between Mirzapur and the United Kingdom's Royal Observatory at Greenwich translates to an exact time difference of 5 hours 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) though the official time-keeping devices are entrusted to the National Physical Laboratory, in New Delhi.

Problems

A single, large time zone has been shown to cost more, and requires rescheduling of events to make them compatible with the rest of the zone or with the day's cycle. The country's east–west distance of more than 2,000 km (1,200 mi) covers over 28 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 north–eastern states have long demanded a separate time zone 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 do allow the Central and State governments to define and set the local time for a particular industrial area.

Time signals

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:

The exact time is broadcast over the state–owned All India Radio and Doordarshan television network. Telephone companies have dedicated phone numbers connected to mirror timeservers that also relay the precise time. Another increasingly popular means of obtaining the time is through Global Positioning System (GPS) receivers.

In popular culture

  • Indians joke about IST as Indian Stretchable Time since some people generally do not stick to time and scheduled events do not follow the timetable that was first set up.
  • IST "Indian Standard Time" can also jokingly refer to arriving late to Indian gatherings or the late start of Indian events. For example, if a concert is scheduled to begin at 7:00 PM, often it will begin no earlier than 8:00 PM, a.k.a. "7:00 PM, IST".
  • Salman Rushdie comments in his novel The Satanic Verses that since India and England are five and a half hours apart, turning an (analogue) watch upside down on one side means that it will accurately display the time on the other.

See also

References

  1. Schmidt, Olaf H. (1944). "The Computation of the Length of Daylight in Hindu Astronomy". Isis, 35(3):205-211. The University of Chicago Press. Retrieved 2006-11-29. {{cite web}}: Italic or bold markup not allowed in: |work= (help)
  2. ^ Burgess, Ebenezer. 1858-1860. "Translation of the Surya-Sikddhanta, A Text-Book of Hindu Astronomy; With Notes, and an Appendix." Journal of the American Oriental Society, 6:141-498. (pages 183-186).
  3. Swerdlow, N. 1973. "A Lost Monument of Indian Astronomy." Isis. 64(2):239-243.
  4. Das, Sukumar Ranjan. 1928. "The Equation of Time in Hindu Astronomy">, The American Mathematical Monthly, 35(10):540-543. Retrieved 1 December 2006.
  5. Piepoli, M. 1997. "Origin of Respiratory Sinus Arrhythmia in Conscious Humans." Circulation. 95:1813-1821. Retrieved 1 December 2006.
  6. Tomczak, Matthias (2004-07-15). "Lecture 7: Living with the seasons—the calendar problem". Lectures on Science, civilization and society, Flinders University, Australia. Retrieved 2006-12-01.
  7. "History of Indian Time (IST)". Greenwich Mean Time (GMT). Retrieved 2006-11-25. {{cite web}}: External link in |work= (help)
  8. "History of Indian Institute of Geomagnetism". National Informatics Centre. 2006-10-10. Retrieved 2006-11-25.
  9. ^ "Odds and Ends". Indian Railways Fan Club. Retrieved 2006-11-25. {{cite web}}: External link in |work= (help)
  10. "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 2006-11-25. {{cite web}}: External link in |work= (help)
  11. "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 2006-11-25. {{cite web}}: URL–wikilink conflict (help)
  12. ^ "India Time Zones". Greenwich Mean Time (GMT). Retrieved 2006-11-25. {{cite web}}: External link in |work= (help)
  13. "Military and Civilian Time Designations". Greenwich Mean Time (GMT). Retrieved 2006-12-02. {{cite web}}: External link in |work= (help)
  14. ^ Sen, Ayanjit (2001-08-21). "India investigates different time zones". BBC News. Retrieved 2006-11-25. {{cite web}}: Check date values in: |date= (help); External link in |work= (help)
  15. S. Muthiah (2002-01-07). "A matter of time". The Hindu Business Line. The Hindu Group. Retrieved 2006-11-25. {{cite web}}: Check date values in: |date= (help); External link in |work= (help)
  16. "Standard Time for Different Regions". Department of Science and Technology]. 2004-07-22. Retrieved 2006-11-25. {{cite web}}: Check date values in: |date= (help)
  17. "A matter of time". National Resource Centre for Women. Retrieved 2006-11-25.
  18. "Indian Time Today (IST)". Greenwich Mean Time (GMT). Retrieved 2006-11-25. {{cite web}}: Cite has empty unknown parameter: |1= (help); External link in |work= (help)
  19. "Satellites for Navigation". Press Information Bureau, Government of India. Retrieved 2006-11-25. {{cite web}}: Cite has empty unknown parameter: |1= (help); External link in |work= (help)
  20. "Tips: Tourism of India". Retrieved 2007-01-21. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  21. "Module 1: Background: General Background". India Unlimited: An Online Tool for Doing Business in India. Center for Asian Studies, The University of Texas at Austin. July 9 2003. Retrieved 2007-01-22. {{cite web}}: Check date values in: |date= (help)

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