Telescope records for the following instruments at Royal Observatory at Greenwich and Herstmonceux: the 13, 26 and 28-inch Refractors and the 30 and 36-inch Reflectors.

The 13-inch Astrographic Refractor was commissioned specifically for the Carte du Ciel. Photography for the project began at Greenwich in 1892 and took 13 years. The precise positions of 179,000 stars were measured from the 1153 photographic plates exposed on the 13-inch refractor. The 26-inch Refractor was constructed in 1896 and between 1897-1988 was used to take c.60,000 large-scale photographs of the night sky. It was mounted with the 30-inch Reflector, together referred to as the Thompson Equatorial Group. The 30-inch Reflector was the largest telescope at Greenwich until the 1930s and was used to photograph comets, asteroids and the satellites of outer planets, and from the 1924/5-1934/5, for spectrographic work (later taken over by the Yapp 36-inch Reflector).

Series 1, telescope records from the Greenwich era, mostly relate to the work at the Royal Observatory Greenwich in compiling the Astrographic Catalogue and Chart (Carte du Ciel). They include: records of adjustment of the 13-inch Refractor, including measurements of coordinates of guiding stars; indexes of chart and catalogue plates; an index and working catalogue of photometry plates; photographic plate records including a measurements of plate trails, lists of prints received, a register of prints reproduced, a register of the dates on which Astrographic chart plates were sent to Paris and a quality control notebook for plates. There are also two bound volumes of Astrographic Catalogue photographic magnitudes. For the 28-inch Refractor, there is a manuscript book of observations of the double star Capella, taken over a three-year period from 1900-1903.

Series 2, telescope records from the Herstmonceux era, covers the 26-inch Refractor, 30-inch Reflector, 13-inch Astrographic Refractor and the 36-inch Yapp Reflector. While the transfer of the Royal Observatory from Greenwich to Herstmonceux began in 1947, these telescopes were not moved until the late 1950s. They were mounted in the new Equatorial Group building, a cluster of domes labelled A to F designed by architect Brian O'Rorke, which was completed in 1958. The records include notes on adjustments and alignments, and records of observations made.

Titles in inverted commas are the original file titles.