Hong Kong Time (abbreviation: HKT; ) is the time in

Hong Kong Hong Kong)., Legally Hong Kong, China in international treaties and organizations. is a special administrative region of China. With 7.5 million residents in a territory, Hong Kong is the fourth most densely populated region in the wor ...

, observed at UTC+08:00 all year round. The

Hong Kong Observatory The Hong Kong Observatory is a weather forecast agency of the government of Hong Kong. The Observatory forecasts the weather and issues warnings on weather-related hazards. It also monitors and makes assessments on radiation levels in Hong ...

is the official

timekeeper A timekeeper is a person that measures the passage of time. They may have additional functions in sports and business. Description A timekeeper is a person who measures time with the assistance of a clock or a stopwatch. Functions Sports In ...

of the Hong Kong Time. It is indicated as Asia/Hong_Kong in the

IANA time zone database The tz database is a collaborative compilation of information about the world's time zones and rules for observing daylight saving time, primarily intended for use with computer programs and operating systems. Paul Eggert has been its editor an ...

Time standards

, 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" () 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+08:00. 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 (LMT) is a form of solar time that corrects the variations of local apparent time, forming a uniform time scale at a specific longitude. This measurement of time was used for everyday use during the 19th century before time zones ...

(GMT+07:36:42) on 1 January 1885 at 13:00 by the then Royal Observatory Hong Kong. In 1904, the

Greenwich Mean Time Greenwich Mean Time (GMT) is the local mean time at the Royal Observatory, Greenwich, Royal Observatory in Greenwich, London, counted from midnight. At different times in the past, it has been calculated in different ways, including being ...

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 (UTC) is the primary time standard globally used to regulate clocks and time. It establishes a reference for the current time, forming the basis for civil time and time zones. UTC facilitates international communicat ...

system was adopted as an official time standard on 1 January 1972. However, the legal Hong Kong Time still remained based on Greenwich Mean Time until it was changed to Universal Standard Time in 1998 after the

Hong Kong handover The handover of Hong Kong from the United Kingdom to the People's Republic of China was at midnight on 1 July 1997. This event ended 156 years of British rule in the former colony, which began in 1841. Hong Kong was established as a special ...

Timekeeping

From 1885, Hong Kong Time was determined by

astronomical observation Observational astronomy is a division of astronomy that is concerned with recording data about the observable universe, in contrast with theoretical astronomy, which is mainly concerned with calculating the measurable implications of physical ...

s at the Hong Kong Observatory using a 6-inch

equatorial mount An equatorial mount is a mount for instruments that compensates for Earth's rotation by having one rotational axis, called ''polar axis'', parallel to the Earth's axis of rotation. This type of mount is used for astronomical telescope mount, tel ...

and a 3-inch Transit Circle. The time was announced to the general public, particularly mariners, by dropping a 6-feet diameter

time ball A time ball or timeball is a time-signalling device. It consists of a large, painted wooden or metal ball that is dropped at a predetermined time, principally to enable navigators aboard ships offshore to verify the setting of their marine chron ...

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 is a natural landform harbor, harbour in Hong Kong separating Hong Kong Island in the south from the Kowloon Peninsula to the north. It acts as both a major trading hub and tourist attraction of Hong Kong in general. Lying in ...

. In January 1908, the time ball was relocated to the hill of

Blackhead Point Blackhead Point (), also known as Tai Pau Mai () indigenously, or by the names Tsim Sha Tsui Point and Signal Hill (), was a cape (geography), cape before any Land reclamation in Hong Kong, land reclamation took place in Tsim Sha Tsui, Kowloon, ...

where it had even higher visibility. With the rise of radio broadcast and the launching of

Radio Hong Kong Radio Television Hong Kong (RTHK) is the public broadcasting service of Hong Kong. GOW, the predecessor to RTHK, was established in 1928 as the first broadcasting service in Hong Kong. As a government department under the Commerce and Economic ...

in 1922, the importance of the time ball decreased. It was decommissioned on 30 June 1933. During the

Second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, the equatorial mount and transit circle were lost. After the war, a

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 an approximate harmonic oscillator: It swings back and forth in a precise time interval dep ...

was installed and regulated by radio time signals from other timekeeping centres. Timing accuracy gradually improved from the daily

engineering tolerance Engineering tolerance is the permissible limit or limits of variation in: # a physical dimension; # a measured value or physical property of a material, manufactured object, system, or service; # other measured values (such as temperature, hum ...

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 A crystal oscillator is an electronic oscillator Electrical circuit, circuit that uses a piezoelectricity, piezoelectric crystal as a frequency selective surface, frequency-selective element. The oscillator frequency is often used to keep trac ...

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 A millisecond (from '' milli-'' and second; symbol: ms) is a unit of time in the International System of Units equal to one thousandth (0.001 or 10−3 or 1/1000) of a second or 1000 microseconds. A millisecond is to one second, as one second i ...

. The frequency standard of the clock is based on the

primary standard A primary standard in metrology is a standard that is sufficiently accurate such 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 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'
Network Time Server
.

Daylight Saving

Hong Kong adopted

daylight saving Daylight saving time (DST), also referred to as daylight savings time, daylight time (United States and Canada), or summer time (United Kingdom, European Union, and others), is the practice of advancing clocks to make better use of the long ...

measures in 1941. However, the practice eventually declined in popularity and was eliminated after 1979.

Time zone serial

Asia/Hong_Kong

References

External links