The Blackett Observatory, is named after Sir Basil Blackett, one time President of the Old Marlburian Club; its telescope (the Barclay) is the largest in full time use in any school.
The observatory is used today to support the GCSE Astronomy course and space modules in the Physics syllabus. All Shell (Year 9) pupils visit the dome in House groups over the first two terms of their time at Marlborough and 'Outreach' encourages use of the dome by those outside the College community. Sir Patrick Moore is president of 'Friends of the Marlborough Telescope', a group of some eighty local observing enthusiasts.
The Barclay Telescope History and Renovation
The Barclay equatorial telescope housed in the observatory is a 10" aperture refractor constructed in 1860 by Thomas Cooke and Sons of York. When built, it was one of the largest telescopes in the UK; it was used professionally for 75 years, first in Essex and then at the Oxford Radcliffe Observatory.
When the Oxford Radcliffe Observatory was being re-sited to South Africa, Sir Basil Blackett raised 800 guineas so that the 10" Barclay Equatorial refractor that had formerly been housed at Oxford could be moved to its current location on the Marlborough College playing fields. It was opened there in 1935 by Harold Knox-Shaw, the last Oxford based Radcliffe Observer.
Starting in 1997, the College funded a five year restoration plan to completely renovate, re-motorise and computerise the main telescope. It is now likely to be the oldest telescope in the world to have a 'go to’ function. The Observatory and telescope were re-opened in October 2002 by Savillian Professor, Joseph Silk FRS.