Time zone, observed in India and Sri Lanka; UTC+05:30
Indian Standard Time
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IST
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17:43, 30 May 2024
IST
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DST is not observed in this time zone.
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Indian Standard Time
(
IST
), sometimes also called
India Standard Time
, is the
time zone
observed throughout the
Republic of India
, with a
time offset
of
UTC+05:30
. India does not observe
daylight saving time
or other seasonal adjustments. In
military and aviation time
, IST is designated
E*
("Echo-Star").
[1]
It is indicated as
Asia/Kolkata
in the
IANA time zone database
.
History
[
edit
]
The Indian Standard Time was adopted on 1 January 1906 during the
British era
with the phasing out of its precursor
Madras Time
(Railway Time),
[2]
and after
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.
[3]
The Central observatory was moved from
Madras
to a location at Shankargarh Fort in
Allahabad district
, so that it would be as close to
UTC+05:30
as possible.
[4]
Daylight Saving Time (DST) was used briefly during the
China?India War of 1962
and the Indo-Pakistani
Wars of 1965
and
1971
.
[5]
Former timezones
[
edit
]
Calculation
[
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]
Indian Standard Time is calculated from the reference longitude of IST at 82°30'E passing near Mirzapur.
[6]
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
.
[7]
This longitude of 82°30'E was chosen as the
standard meridian
for the whole country
[8]
as it is located centrally between
western India
(
local time UTC +05:00
) and
northeastern India
(
local time UTC +06:00
). Currently, the
Council of Scientific and Industrial Research- National Physical Laboratory
(CSIR-NPL) maintains the Indian Standard Time with the help of the
Allahabad Observatory
.
[9]
Criticism and proposals
[
edit
]
The country's east?west distance of more than 2,933 kilometres (1,822 mi) covers over 29° 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 to avoid the extra consumption of energy after daylight hours.
[6]
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, but the recommendations were not adopted.
[6]
[10]
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.
[6]
The findings of the committee, which were presented to
Parliament
in 2004 by the Minister of 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.'
[11]
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.
[12]
In
Assam
, tea gardens follow a separate time zone, known as the
Chaibagan
or
Bagan
time ('Tea Garden Time'), which is one hour ahead of IST.
[13]
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
northeastern states
of India.
[14]
[15]
However, the proposal would need to be cleared by the
union government
.
In June 2017, the
Department of Science and Technology
(DST) indicated that it is once again studying the 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.
[16]
[
needs update
]
Time signals
[
edit
]
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 synchronised with the worldwide system of clocks that support
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
?10
.
- 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.
[17]
See also
[
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]
References
[
edit
]
External links
[
edit
]