Solar Data
- Greenwich Sunspot Group Reports
1874 to 1981 - Mount Wilson Sunspot Group Reports
1962 to 1999 - USAF observatory (and Mt.Wilson) Sunspot
Group Reports
1981 - 1999 - Royal Observatory Greenwich Photo
Heliographic Results
1874 - 1976 - Solar Images on glass and print 1903 - 1942: Online catalogue