The Poker Flat Research Range (PFRR) is a launch facility and rocket range for sounding rockets in the U.S. state of Alaska, located on a 5,132-acre (20.77 km2) site at Chatanika, about 30 miles (50 km) northeast of Fairbanks and 1.5 degrees south of the Arctic Circle. More than 1,700 launches have been conducted at the range to study the Earth's atmosphere and the interaction between the atmosphere and the space environment. Areas studied at PFRR include the aurora, plasma physics, the ozone layer, solar proton events, Earth's magnetic field, and ultraviolet radiation. Rockets launched at PFRR have attained an apogee of 930 miles (1,500 km).