The Royal Greenwich Observatory (RGO) was founded at Greenwich in London in 1675 by King Charles II but was moved just after the second world war in order to escape the lights and pollution of the city. The site at Herstmonceux was chosen as the most suitable in the UK. By the mid-fifties the observatory was fully operational. The existing telescopes were augmented in 1967 by the giant 98-inch Isaac Newton Telescope (INT) once housed in the silver dome to the south of the main complex.


During its days at Herstmonceux, the RGO built up an enviable reputation for world-class astronomical research. Each year Herstmonceux Castle was the venue for a major conference attracting top astronomers from all over the world.







RGO was also responsible for more routine work, involving the careful mapping of star positions, monitoring of solar activity and provision of a national time service. It was from the observatory's atomic clocks at Herstmonceux that the familiar 'six-pips' were sent by land-line to the BBC for broadcast. Today, the BBC generates the 'pips' for themselves. Another facet of the RGO's work was the production of annual almanacs which contained the carefully computed positions of the sun, moon, planets and stars for every day of the year. This work was carried out jointly with the US Naval Observatory in Washington, DC.


Unfortunately, even Herstmonceux is not a good astronomical site in world terms and the unreliable UK weather meant that the Isaac Newton Telescope (INT) could not be utilised as much as it should have been. With the advent of cheap air travel in the sixties it became feasible for astronomers to travel to other observatories in order to use telescopes in the best possible locations. Eventually, the decision was taken to establish a major overseas observatory in the northern hemisphere and to move the INT there, where it could be put to better use.


In 1979 the telescope was dismantled, removed from its dome and completely refurbished before being installed on top of an extinct volcano on the Canary Island of La Palma in 1984. Here it forms part of the International 'Roque de los Muchachos Observatory' run as an overseas facility by the Royal Greenwich Observatory.


With its main telescopes located abroad, resources for maintaining the instruments at Herstmonceux diminished and they were used less and less. Eventually, the decision was taken to move the Observatory again, this time to a new site at Cambridge, adjacent to the University's Institute of Astronomy. The Observatory moved to Cambridge in 1990 leaving behind the Equatorial Group of Telescopes.


When the estate passed into the hands of Queen's University of Kingston, Ontario, Canada, Science Projects (a company with charitable status) proposed the idea of a 'hands-on' science centre, located in the old telescope buildings. The proposal was backed by both the local district and county councils and, as a forerunner to the permanent centre, a travelling exhibition known as the Discovery Dome visited the site for three months during the summer of 1994.


The Observatory Science Centre  opened in April 1995. The domes and buildings and telescopes are being renovated and the Centre is a major venue for exhibitions, lectures and educational programmes. Research and training facilities are being developed in conjunction with local universities, colleges and technology-based businesses. The renovated telescopes are providing a unique facility for schools, colleges and astronomical societies.







Although the Royal Greenwich Observatory vacated the Herstmonceux site in 1990, one part of it still remains operational - the Satellite Laser Ranger or SLR.


From its foundation in 1675 the Royal Greenwich Observatory (RGO) has been at the forefront of improving techniques for navigation- the problem of accurately determining where you are on the Earth's surface- and also how far you are above or below it. Until quite recently navigators at sea relied heavily on observations of stars to fix their positions while land surveyors set up networks of carefully measured reference markers which are a familiar sight on many hill tops. However, with the dawning of the space age, man-made satellites orbiting the Earth have come to play an ever more crucial role in navigation.


Satellite Laser Ranging (SLR) is a particularly accurate method of measuring distances by bouncing a laser beam off special satellites carrying highly efficient mirrors called retro-reflectors

The basic principle of SLR is very simple. A telescope tracks the satellite as it orbits overhead and fires a very short burst of laser light towards it. As each burst leaves the telescope it starts a timer. The burst travels up to the satellite where a retro-reflector bounces it back to the telescope again where it stops the timer. Since the speed of light is very accurately known, the time it takes for the laser light to travel to the satellite and back can be converted to give the distance.



The 26-Inch Thompson Telescope     Satellite Tracking at Herstmonceux      Throwing Some Light on the Mysteries of the Universe




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