The Green Bank Radio Telescope is positioned in a basin surrounded by mountains and protected by law from radio broadcasts (no cell phone service). The free tour offered to tourists covers this subject extensively including several stories about 'problems' they have had with static from such things as a faulty electric blanket. Battery operated devices, including digital cameras, are not allowed inside the immediate area of the telescope due to radio interference. The (diesel) tour bus stops at the last 'safe' position so anyone wishing to get off and take a photo may do so. Non-battery film cameras are allowed right up to the dish. The next time I go, I will take an old film camera for this purpose. Scale is hard to convey in a photo but the dish is 2.3 acres in area and would hold a football field.