The Isaac Newton Telescope started operations in Herstmonceux, United Kingdom, in 1967, but after a number of years it became clear that better astronomical weather conditions would benefit the astronomical use of the telescope. Such conditions are found on the Roque de Los Muchachos Observatory on La Palma (Canary Islands, Spain) and therefore it was decided to move the telescope to La Palma, where it resumed operations in 1984.
The Isaac Newton Telescope has a 2.5-metre primary mirror. It uses a polar-disc and fork type of equatorial mount. Instruments can be mounted either at the Prime focus or the Cassegrain focus, and they offer the possibility of carrying out both wide-field imaging and intermediate to low dispersion spectroscopy. The Wide Field Camera is an advanced instrument which offers unique opportunities to execute deep, wide-field optical-imaging surveys. It consists of a CCD mosaic covering nearly a half-degree field of view, or approximately the angular size of the Moon.
The number of scientific highlights obtained using the Isaac Newton Telescope over the years is very high. The telescope has made many important contributions to the research of quasars, supernovas, black holes, dwarf galaxies, the Milky Way, planetary nebulae, and star evolution. The first ever observational evidence of the existence of a black hole in the Milky Way Galaxy is one of the most outstanding results obtained using the Isaac Newton Telescope.