Scope and Contents RGO 50 is the product of a solar observation programme begun in 1873 at the Royal Observatory, Greenwich and continued, from 1953 to 1979, at Royal Greenwich Observatory, Herstmonceux. It primarily consists of a sequence of glass plate negatives of daily observations. Where no plate was produced at Greenwich or Herstmonceux the gap has been filled by sourcing plates from observatories elsewhere around the world, particularly the Indian observatories at Kodaikanal and Dehra Dūn. Observation...