The Isaac Newton Telescope or INT is a 2.54 m (100 in) optical telescope run by the Isaac Newton Group of Telescopes at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984. Originally the INT was situated at Herstmonceux Castle in Sussex, England, which was the site of the Royal Greenwich Observatory after it moved away from Greenwich due to light pollution. It was inaugurated in 1967 by Queen Elizabeth II. Herstmonceux suffered from poor weather, and the advent of mass air travel made it plausible for UK astronomers to run an overseas observatory. In 1979, the INT was shipped to La Palma, where it has remained ever since. It saw its second first light in 1984, with a video camera. A major change was the mirror was now made of the new type Zerodur glass, as compared to the old mirror's Pyrex glass. Today, it is used mostly with the Wide Field Camera (WFC), a four CCD instrument with a field of view of 0.56×0.56 square degrees which was commissioned in 1997. The other main instrument available at the INT is the intermediate dispersion spectrograph (IDS), recently re-introduced, having been unavailable for a period of several years. The old site of the INT is now the Observatory Science Center at Herstmonceux, and it is known for its distinctive greened copper dome and various science and astronomy activities. Summary Background up to 1979 The United States gifted a 98-inch mirror in 1949 to the United Kingdom. (In a telescope this could establish the 3rd largest in the World, behind only the Hale and Hooker telescopes at that time). After ten years the mount was ordered for the telescope, and in 1959 construction began on what would be the INT, and it was completed by 1965; first light at Herstmonceux was conducted that year. The mirror was ground by Grubb in the 1950s, although until 1956, according to Observatories and Telescopes of Modern Times, there was some consideration for buying a new 74-inch from Grubb. The Royal Greenwich Observatory completed its move to Herstmonceux in 1956. A short film was published in 1956 that featured the grinding of the 98-inch mirror blank for the Isaac Newton Telescope by Grubb Parsons. (reflecting telescopes of this type need the glass blank ground into a precise shape, which can take years) The telescope's first light (first, first light) occurred