The diaries were used by GE Perry to record daily duties and appointments as well as satellite predictions and observations. The early diaries also contain the details of sent and received correspondence. Information on school lessons is present in the diaries until GE Perry's retirement in 1984. Other entries include visits, speaking engagements, interviews, and key events. The satellite observations and predictions are typically recorded in the page margins and underlined if the satelites were observed. Post 1988, diaries are accompanied by pocket diaries or calendars providing additional details on the satellite observations.