The collection includes papers of the Solar Department of the Royal Greenwich Observatory between 1890 and 1987. The Solar Department, which was concerned with spectroscopy and daily photography of the sun, was founded in 1873. The papers include scientific observations, notebooks, and registers; administrative documents; correspondence; notes on procedures and equipment; and some personal papers, including early notebooks by H. W. Newton and John and Sydney Evershed. There are also observations shared with the RGO by other observatories. The Observatory moved from Greenwich to Herstmonceux in Sussex beginning in 1948. The Solar Department published its data in the Solar Activity Circulars and Greenwich Photoheliograph Results. The data service was formally closed in 1979.