Earlier reference papers
Galileo's observations of Neptune were identified by Charles Kowal and
Stillman Drake in 1979. A very enjoyable paper on the subject here:
http://www.dioi.org/Kowal-Galileo.pdf
http://www.nature.com/nature/journal/v287/n5780/abs/287311a0.html
S. Drake and C. T. Kowal "Galileo's Sighting of Neptune" Scientific American 243(6), 52-59 (1980)
Further observations were identified by E. M. Standish and A. M. Nobili:
Standish, E.M. & Nobili, A.M. "Galileo's observations of Neptune" Baltic
Astronomy, vol.6 (1997) 97-104
