Charles Bartholemew “Ben” Gascoigne AO (11 November 1915 – 25 March 2010) was one of the leading figures in the design and commissioning of the Anglo-Australian Telescope, Australia's largest optical telescope and once one of the world's most important astronomy facilities. He was also an optical astronomer and photometrist. Born in Napier, New Zealand during World War II, Gascoigne completed his education in Auckland and the University of Bristol before leaving for Australia to work at the Commonwealth Solar Observatory on Mount Stromlo in Canberra. He developed expertise in the design and manufacture of optical components such as telescope elements.
After the war, Gascoigne and astronomer Gerald Kron discovered using newly developed telescopes on Mount Stromlo that the distance between our galaxy and the dwarf galaxies in the Magellanic Cloud was overestimated by a factor of two. As this measurement is used to calibrate other distances in astronomy, the result has doubled the estimated size of the universe. They also discovered that star formation in the Magellanic Clouds occurred more recently than in the Milky Way; this refuted the traditional belief that the two occurred simultaneously.
A key figure at Mount Stromlo Observatory, Gascoigne played a key role in transforming the observatory from a solar observatory to a stellar and galactic research center. He also played an important role in establishing the Siding Spring Observatory in northern New South Wales. Gascoigne was involved from the very beginning of the long commissioning of the Anglo-Australian Telescope, which the British and Australian governments decided to jointly build at Siding Spring. He also took the first photograph of the telescope. Gascoigne was awarded the Order of Australia for his services to astronomy and to the Anglo-Australian Telescope.
Gascoigne and his wife, artist Rosalie Gascoigne, had three children. After Gascoigne retired, he published a series of books on the history of Australian astronomy. He served as Rosalie's photographer and assistant, using her technical expertise to help prepare her artworks for public exhibitions.