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{{Use dmy dates}} | {{short description|Time zone, observed in India and Sri Lanka; UTC+05:30}}{{For|Irish Standard Time|Time in the Republic of Ireland}} | ||
{{Use dmy dates|date=August 2017}} | |||
{{Use Indian English|date=August 2017}} | |||
{{infobox time zone | {{infobox time zone | ||
| title = Indian Standard Time | | title = Indian Standard Time | ||
| caption = {{legend|#b7ec6d|Indian Standard Time}} | | caption = {{legend|#b7ec6d|Indian Standard Time}} | ||
| offset = +05:30 | | offset = +05:30 | ||
| Line 9: | Line 11: | ||
| display observance = yes | | display observance = yes | ||
}} | }} | ||
'''Indian Standard Time''' (IST) is the [[time zone]] | '''Indian Standard Time''' ('''IST'''), sometimes also called '''India Standard Time''', is the [[time zone]] observed throughout [[India]], with a [[time offset]] of [[UTC+05:30]]. India does not observe [[daylight saving time]] or other seasonal adjustments. In [[List of military time zones|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 |access-date= 2006-12-02 |work=Greenwich Mean Time}}</ref> It is indicated as Asia/Kolkata in the [[Tz database|IANA time zone database]]. | ||
==History== | |||
{{Main|Time in India}} | |||
After [[Indian Independence movement| Independence in 1947]], the [[Union 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.<ref name="Princely states">{{cite web|url=http://www.irfca.org/faq/faq-misc.html |title=Odds and Ends |access-date=2006-11-25 |publisher=Indian Railways Fan Club}}</ref> 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.<ref name="Hans 2018">{{cite news |title=India Standard Time |url=https://www.thehansindia.com/posts/index/Hans-Classroom/2018-04-19/India-Standard-Time/374988 |access-date=27 June 2021 |work=The Hans India |publisher=Hyderabad Media House Limited |date=19 April 2018}}</ref> | |||
Daylight Saving Time (DST) was used briefly during the [[Sino-Indian War|China–India War of 1962]] and the Indo-Pakistani [[Indo-Pakistani War of 1965|Wars of 1965]] and [[Indo-Pakistani War of 1971|1971]].<ref name="timez">{{cite web |url =http://wwp.india-time.com/indian-time-zones.htm |title =India Time Zones |access-date =2006-11-25 |work =Greenwich Mean Time |url-status =dead |archive-url =https://web.archive.org/web/20070519085807/http://wwp.india-time.com/indian-time-zones.htm |archive-date =19 May 2007 |df =dmy-all }}</ref> | |||
==Calculation== | |||
[[File:IST-Mirzapur.svg|thumb|Location of Mirzapur (near Allahabad) and the 82.5° E longitude that is used as the reference longitude for IST]] | |||
Indian Standard Time is calculated from [[Ghanta Ghar, Mirzapur|the clock tower in Mirzapur]] nearly exactly on the reference longitude of IST at 82°30'E, within 4 angular minutes.<ref>{{cite news |title=India investigates different time zones |url=http://news.bbc.co.uk/2/hi/south_asia/1501252.stm |access-date=15 March 2021 |work=BBC |date=21 August 2001}}</ref> In 1905, the meridian passing east of Allahabad was declared as a standard time zone for [[British India]] and was declared as IST in 1947 for the [[dominion of India]].<ref>{{cite news |title=September 1, 1947: How Indian Standard Time was introduced in country |url=https://www.timesnownews.com/mirror-now/in-focus/article/september-1-1947-how-indian-standard-time-was-introduced-in-country/806185 |access-date=19 April 2022 |work=www.timesnownews.com |language=en}}</ref> The longitude of 82°5'E passing through Naini near [[Allahabad]] was chosen as the [[standard meridian]] for the whole country,<ref>{{cite news |title=Indian Standard Time: Lack of scientific temper |url=https://timesofindia.indiatimes.com/readersblog/nishant-chandravanshi/indian-standard-time-lack-of-scientific-temper-33370/ |access-date=19 April 2022 |work=Times of India Blog |date=10 June 2021 |language=en}}</ref> because there is a time lag of more than a hour between [[western India]] ([[UTC+05:00|around +05:00]]) and [[northeastern India]] ([[UTC+06:00|around +06:00]]), hence approximately standardizing with [[UTC+05:30]] of [[Central Zonal Council|central India]]. Currently, the [[National Physical Laboratory of India|Council of Scientific and Industrial Research- National Physical Laboratory]] (CSIR-NPL) maintains the Indian Standard Time with the help of the [[Allahabad Observatory]].<ref>{{cite news |title=How Indian Standard Time was introduced in India on September 1, 1947 - Explained |url=https://www.jagranjosh.com/current-affairs/how-indian-standard-time-was-introduced-in-country-on-september-1-1947-explained-1630493926-1 |access-date=19 April 2022 |work=Jagranjosh.com |date=1 September 2021}}</ref> | |||
==Criticism and proposals== | |||
The country's east–west distance of more than {{convert|2,933|km|mi}} 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 [[Northeast India|northeastern states]] have to advance their clocks with the early sunrise and avoid the extra consumption of energy after daylight hours.<ref name="bbc">{{cite web |url=http://news.bbc.co.uk/2/hi/south_asia/1501252.stm |title=India investigates different time zones|access-date=2006-11-25 |last=Sen |first=Ayanjit |date=2001-08-21 |work=BBC News}}</ref> | |||
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.<ref name="bbc"/><ref name="thehindu2002">{{cite web|url=http://www.hindu.com/thehindu/mp/2002/01/07/stories/2002010700130300.htm |archive-url=https://web.archive.org/web/20020324174028/http://hindu.com/thehindu/mp/2002/01/07/stories/2002010700130300.htm |url-status=dead |archive-date=2002-03-24 |title=A matter of time |access-date=2006-11-25 |last=S. Muthiah |date=2012-09-24 |work=[[The Hindu]] }}</ref> | |||
In 2001, the government established a four-member committee under the [[Department of Science and Technology (India)|Ministry of Science and Technology]] to examine the need for multiple time zones and daylight saving.<ref name="bbc"/> The findings of the committee, which were presented to [[Parliament of India|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."<ref>{{cite web |url=http://dst.gov.in/admin_finance/un-sq1007.htm |title=Standard Time for Different Regions |access-date=2006-11-25 |date=2004-07-22 |work=Department of Science and Technology |url-status=dead |archive-url=https://web.archive.org/web/20070928010543/http://dst.gov.in/admin_finance/un-sq1007.htm |archive-date=28 September 2007 |df=dmy-all }}</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'' allow the Union 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 |access-date=2006-11-25 |work=National Resource Centre for Women |url-status=dead |archive-url=https://web.archive.org/web/20060319181936/http://nrcw.nic.in/shared/sublinkimages/19.htm |archive-date=19 March 2006 |df=dmy-all }}</ref> 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.<ref name="HindustanTimes2008">{{cite web |url=http://www.hindustantimes.com/News-Feed/India/Change-clock-to-bagantime/Article1-304181.aspx |title=Change clock to bagantime |access-date=2008-09-22 |last=Rahul Karmakar |date=2012-09-24 |work=[[Hindustan Times]] |url-status=dead |archive-url=https://web.archive.org/web/20110606065730/http://www.hindustantimes.com/News-Feed/india/Change-clock-to-bagantime/Article1-304181.aspx |archive-date=6 June 2011 |df=dmy-all }}</ref> Still Indian Standard Time remains the only officially used time. | |||
In 2014, Chief Minister of Assam [[Tarun Gogoi]] started campaigning for another time zone for [[Assam]] and other [[northeast India|northeastern states]] of India.<ref>{{Cite news|url=https://timesofindia.indiatimes.com/india/Gogoi-for-separate-time-zone-for-Assam/articleshow/28252502.cms?referral=PM|title=Gogoi for separate time zone for Assam - Times of India|work=The Times of India|access-date=2018-05-10}}</ref><ref>{{cite web|url=http://www.ndtv.com/article/india/india-could-get-second-time-zone-with-assam-one-hour-ahead-466326?curl=1388743528|title=India could get second time zone with Assam one hour ahead|website=ndtv.com}}</ref> However, the proposal would need to be cleared by the [[Union Government]]. | |||
In June 2017, [[Department of Science and Technology (India)|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.<ref>{{Cite news|url=http://economictimes.indiatimes.com/news/politics-and-nation/government-assessing-feasibility-of-different-time-zones-in-india/articleshow/59268686.cms|title=Government assessing feasibility of different time zones in India|date=2017-06-22|work=The Economic Times|access-date=2017-08-18}}</ref>{{update needed|date=February 2020}} | |||
==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 clock]]s 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 ''ATA'' to 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<sup>−10</sup>. | |||
*Time and frequency calibrations made with the help of [[picosecond|pico-]] and [[nanosecond]]s time interval [[frequency counter]]s and [[phase (waves)|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 server]]s that also relay the precise time. Another increasingly popular means of obtaining the time is through [[Global Positioning System]] (GPS) receivers.<ref>{{cite web|url=http://pib.nic.in/release/rel_print_page.asp?relid=19703 |title=Satellites for Navigation |access-date=2006-11-25 |work=Press Information Bureau, Government of India}}</ref> | |||
==See also== | |||
*[[Bombay Time]] | |||
*[[Calcutta Time]] | |||
*[[Equation of time]] | |||
*[[International Atomic Time]] | |||
*[[John Goldingham]] | |||
*[[Madras Time]] | |||
*[[Port Blair mean time]] | |||
*[[Punctuality]] | |||
*[[Railway time#India|Railway time in India]] | |||
*[[Sri Lanka Standard Time]] | |||
*[[Terrestrial Time]] | |||
*[[Time in Afghanistan]] | |||
*[[Time in India]] | |||
*[[Time in Sri Lanka]] | |||
*[[Time zone]] ([[Lists of time zones|list]]) | |||
*[[UTC+05:30]] | |||
*[[Zoneinfo]] | |||
==References== | ==References== | ||
* [http:// | {{Reflist|2}} | ||
==External links== | |||
*[http://www.nplindia.org/ National Physical Laboratory] | |||
*[http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.394.7155&rep=rep1&type=pdf ''Evaluating two timezones<nowiki>[sic]</nowiki> and Daylight Saving Time for India''], by Viral Shah & Vikram Aggarwal. | |||
{{Asia topic|Time in}} | |||
{{ | |||
[[Category:Time in India]] | |||
[[Category:Geography of India]] | |||
[[Category:Time zones]] | [[Category:Time zones]] | ||