Hong Kong Time
Encyclopedia
Hong Kong Time is the time in Hong Kong
, observed at UTC+8
all year round. The Hong Kong Observatory
is the official timekeeper
of the Hong Kong Time.
Section 67(2) of the Ordinance states that:
Currently, Hong Kong time is defined as UTC+8
. The reference in section 67(2) to the Oil (Conservation and Control) Ordinance is actually a power given to the Legislative Council of Hong Kong to change Hong Kong Time for the purposes of conserving oil, i.e. to implement daylight saving time. However, no daylight saving time has been observed since 1979.
The Hong Kong Time was first set to Local Mean Time
(GMT+7:36:41) on 1 January 1885 at 13:00 by the then Royal Observatory Hong Kong. In 1904, the Greenwich Mean Time
was adopted as the basis for Hong Kong Time, the time was set at 8 hours in advance of Greenwich Mean Time. The current Coordinated Universal Time
system was adopted as an official time standard on 1 January 1972. However, the legal Hong Kong Time still remained under Greenwich Mean Time until it was changed to Universal Standard Time after the Hong Kong handover in 1998.
Since 1885, Hong Kong Time was determined by astronomical observations at the Hong Kong Observatory using a 6-inch equatorial mount
and a 3-inch Transit Circle. The time was announced to the general public, particularly mariners, by dropping a 6-feet diameter time ball
from a mast exactly at 13:00 daily in front the Marine Police Headquarters Compound, where it is visible from the Victoria Harbour
. In January 1908, the time ball was relocated to the hill of Blackhead Point
where it had even higher visibility. With the rise of radio broadcast and the launching of Radio Hong Kong in 1922, the importance of the time ball decreased. It was decommissioned on 30 June 1933.
During the Second World War, the equatorial mount and transit circle were lost. After the war, a pendulum clock
was installed and regulated by radio time signals from other timekeeping centres. Timing accuracy gradually improved from the daily engineering tolerance of a few seconds to one-fifth of a second.
In 1966, the pendulum clock in the Royal Observatory Hong Kong was replaced by a crystal oscillator
timing system. In the same year, the Royal Observatory started to broadcast the time directly with a 6-pip time signal on 95 MHz. This continued until 16 September 1989.
In 1980, the Royal Observatory adopted a timing system based on a Caesium beam atomic clock. This system narrowed the engineering tolerance down to less than 1 millisecond
. The frequency standard of the clock is based on the primary standard
used by Japan's Communications Research Laboratory. In 1994, the atomic clock was replaced with a newer model.
Current Hong Kong Time can be obtained from the Observatory's Network Time Server.
measures in 1941. However, in the 1970s, the government found these measures unnecessary as Hong Kong is at a relatively low latitude. The practice was eliminated in 1979.
Hong Kong
Hong Kong is one of two Special Administrative Regions of the People's Republic of China , the other being Macau. A city-state situated on China's south coast and enclosed by the Pearl River Delta and South China Sea, it is renowned for its expansive skyline and deep natural harbour...
, observed at UTC+8
UTC+8
UTC+08:00 is an identifier for a time offset from UTC of +08:00. In ISO 8601 the associated time would be written as .With an estimated population of 1.53 billion living within the time zone, roughly 22.5% of the world population, it is the most populous time zone in world, as well as a possible...
all year round. The Hong Kong Observatory
Hong Kong Observatory
Hong Kong Observatory is a department of the Hong Kong government. The Observatory forecasts weather and issues warnings on weather-related hazards...
is the official timekeeper
Timekeeper
A timekeeper is an instrument or person that measures the passage of time; in the case of the latter, often with the assistance of a clock or stopwatch...
of the Hong Kong Time.
Time standards
In Hong Kong, Hong Kong Time is defined in the Interpretation and General Clauses Ordinance (Cap 1), Laws of Hong Kong.Section 67(2) of the Ordinance states that:
"Hong Kong Time" (香港時間) means the time used for general purposes throughout Hong Kong namely, 8 hours, or such other period as may be determined by the Legislative Council by resolution under this subsection or under section 16 of the Oil (Conservation and Control) Ordinance (Cap 264), in advance of Universal Standard Time.
Currently, Hong Kong time is defined as UTC+8
UTC+8
UTC+08:00 is an identifier for a time offset from UTC of +08:00. In ISO 8601 the associated time would be written as .With an estimated population of 1.53 billion living within the time zone, roughly 22.5% of the world population, it is the most populous time zone in world, as well as a possible...
. The reference in section 67(2) to the Oil (Conservation and Control) Ordinance is actually a power given to the Legislative Council of Hong Kong to change Hong Kong Time for the purposes of conserving oil, i.e. to implement daylight saving time. However, no daylight saving time has been observed since 1979.
The Hong Kong Time was first set to Local Mean Time
Local mean time
Local mean time is a form of solar time that corrects the variations of local apparent time, forming a uniform time scale at a specific longitude...
(GMT+7:36:41) on 1 January 1885 at 13:00 by the then Royal Observatory Hong Kong. In 1904, the Greenwich Mean Time
Greenwich Mean Time
Greenwich Mean Time is a term originally referring to mean solar time at the Royal Observatory in Greenwich, London. It is arguably the same as Coordinated Universal Time and when this is viewed as a time zone the name Greenwich Mean Time is especially used by bodies connected with the United...
was adopted as the basis for Hong Kong Time, the time was set at 8 hours in advance of Greenwich Mean Time. The current Coordinated Universal Time
Coordinated Universal Time
Coordinated Universal Time is the primary time standard by which the world regulates clocks and time. It is one of several closely related successors to Greenwich Mean Time. Computer servers, online services and other entities that rely on having a universally accepted time use UTC for that purpose...
system was adopted as an official time standard on 1 January 1972. However, the legal Hong Kong Time still remained under Greenwich Mean Time until it was changed to Universal Standard Time after the Hong Kong handover in 1998.
Timekeeping
Equatorial mount
An equatorial mount is a mount for instruments that follows the rotation of the sky by having one rotational axis parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescopes and cameras...
and a 3-inch Transit Circle. The time was announced to the general public, particularly mariners, by dropping a 6-feet diameter time ball
Time ball
A time ball is a large painted wooden or metal ball that drops at a predetermined time, principally to enable sailors to check their marine chronometers from their boats offshore...
from a mast exactly at 13:00 daily in front the Marine Police Headquarters Compound, where it is visible from the Victoria Harbour
Victoria Harbour
Victoria Harbour is a natural landform harbour situated between Hong Kong Island and the Kowloon Peninsula in Hong Kong. The harbour's deep, sheltered waters and strategic location on the South China Sea were instrumental in Hong Kong's establishment as a British colony and its subsequent...
. In January 1908, the time ball was relocated to the hill of Blackhead Point
Blackhead Point
Blackhead Point , also known as Tai Pau Mai indigenously, Tsim Sha Tsui Point or Signal Hill , was a cape before any reclamation in Tsim Sha Tsui, Kowloon, Hong Kong...
where it had even higher visibility. With the rise of radio broadcast and the launching of Radio Hong Kong in 1922, the importance of the time ball decreased. It was decommissioned on 30 June 1933.
During the Second World War, the equatorial mount and transit circle were lost. After the war, a pendulum clock
Pendulum clock
A pendulum clock is a clock that uses a pendulum, a swinging weight, as its timekeeping element. The advantage of a pendulum for timekeeping is that it is a resonant device; it swings back and forth in a precise time interval dependent on its length, and resists swinging at other rates...
was installed and regulated by radio time signals from other timekeeping centres. Timing accuracy gradually improved from the daily engineering tolerance of a few seconds to one-fifth of a second.
In 1966, the pendulum clock in the Royal Observatory Hong Kong was replaced by a crystal oscillator
Crystal oscillator
A crystal oscillator is an electronic oscillator circuit that uses the mechanical resonance of a vibrating crystal of piezoelectric material to create an electrical signal with a very precise frequency...
timing system. In the same year, the Royal Observatory started to broadcast the time directly with a 6-pip time signal on 95 MHz. This continued until 16 September 1989.
In 1980, the Royal Observatory adopted a timing system based on a Caesium beam atomic clock. This system narrowed the engineering tolerance down to less than 1 millisecond
Millisecond
A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....
. The frequency standard of the clock is based on the primary standard
Primary standard
A primary standard in metrology is a standard that is accurate enough that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working...
used by Japan's Communications Research Laboratory. In 1994, the atomic clock was replaced with a newer model.
Current Hong Kong Time can be obtained from the Observatory's Network Time Server.
Daylight Saving
Hong Kong adopted daylight savingDaylight saving time
Daylight saving time —also summer time in several countries including in British English and European official terminology —is the practice of temporarily advancing clocks during the summertime so that afternoons have more daylight and mornings have less...
measures in 1941. However, in the 1970s, the government found these measures unnecessary as Hong Kong is at a relatively low latitude. The practice was eliminated in 1979.