The Lockman Hole is an area of the sky which is like a clear window into far distant space.
From our position in the Milky Way galaxy, most directions are partly blocked or obscured by H I clouds of neutral hydrogen. These glow faintly with infrared light and obscure distant views at extreme ultraviolet and soft x-ray wavelengths.
The H I clouds interfere with observations at those wavelengths in nearly all other directions. So the Lockman Hole is an attractive area of the sky for observational astronomy surveys. It is near the pointer stars of the Big Dipper in the constellation Ursa Major. is about 15 square degrees in size, and is named after its discoverer, astronomer Jay Lockman.