Thule neutron monitor, oldest of the monitors operated by Bartol Research Institute, began collecting data in 1957. The neutron detector tubes are inside the four white boxes encased in polyethylene. The three smaller boxes at left each contain three detector tubes of the traditional "BP28" design, which uses boron trifluoride to capture neutrons. The larger box at right was added in 2001. It contains nine tubes of a newer design that uses helium-3 to capture neutrons. Photo by J Roth, 2001.

• Thule Weather
• Greenland Tourism Guide.
• Michael Salling's Thule site.

Building 561 on Thule Air Force Base, Greenland, home of the Thule neutron monitor since August 20, 1997. Photo by L Shulman, 1999.