The photoheliographic programme of the Royal Observatory ran from 1873-1948 at Greenwich and from 1948-1976 at Herstmonceux, when it was ended by Sir Richard Woolley.

The main series of the collection (RGO 157/2) is comprised of printed historical volumes of Greenwich Photo-heliographic Results (GPR), which include daily measurements of sunspot positions and the areas of sunspots and faculae observed from 1874 to 1976. Prior to 1948 the GRP volumes were published by the Royal Observatory, Greenwich and thereafter by the Royal Greenwich Observatory (Herstmonceux). In 1976 the program of daily solar observations was transferred to the Debrecen Observatory of the Hungarian Academy of Sciences. The printed run of Greenwich Photo-heliograph results preserved here include results for 1874-1875, 1893, 1897, 1901-1904, 1906, 1911, 1914-1922, and 1924-1955.

The collection also includes a number of sets of handwritten registers on printed forms. These are organised by title and form number. They include:

RGO 157/1: Registers of 'Mean areas and mean latitudes of sun spots for each rotation of the Sun' (Form No. 247 and 247*), 1873-1958 - an incomplete sequence.

RGO 157/3: Reductions of Carrington's Catalogue from 1855 to 1900.

RGO 157/4: A single register of Areas of Sun-Spots for each degree of Heliographic Latitude and for each Rotation of the Sun' (Form No. 246*).

RGO 157/5: Registers of Solar Photographs, Royal Observatory, Cape of Good Hope; a continuous run of registers of solar photographs, covering plate nos. 1-27804, 1910-1951.

RGO 157/6: Registers of 'Determination of Elements for Photographs of the Sun' (Form No. 229); a continuous run from 1936 to 1964.

RGO 157/7: A single register of 'Measures of Positions and Areas of Sun Spots and Faculae' (Form No. 230), 1941.

RGO 157/8: Two registers of 'Weighted Mean Latitudes of [Sun] Spot Groups' (Form No.319*), 1947 and 1957.

The collection also includes 17 bundles of solar interference charts for January 1969 to 21 October 1979, showing 'Sudden Enhancements of Atmospheric (SEA)' and 'Sudden Ionospheric Disturbances' (SID) (RGO 157/9).

Catalogued by Dr Emma Saunders in 2025.