Big Bear Solar Observatory

Big Bear Solar Observatory

Old dome on the main BBSO building
Organization	New Jersey Institute of Technology
Code	G77
Location	Big Bear Lake, United States of America
Coordinates	34°15′30″N 116°55′16″W / 34.2583°N 116.921°W / 34.2583; -116.921Coordinates: 34°15′30″N 116°55′16″W / 34.2583°N 116.921°W / 34.2583; -116.921
Altitude	2,060 m (6,760 ft)
Established	1969
Website	www.bbso.njit.edu
Telescopes
New Solar Telescope 1.6 m reflector FDHA telescope 10 cm refractor
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The Big Bear Solar Observatory (BBSO) is a solar observatory located on the north side of Big Bear Lake in the San Bernardino Mountains of southwestern San Bernardino County, California (USA), approximately 120 kilometers (75 mi) east of downtown Los Angeles. The telescopes and instruments at the observatory are designed and employed specifically for studying the activities and phenomena of our solar system's star, the Sun.

The observatory was built by the California Institute of Technology in 1969 under the direction of professor Harold Zirin. Management of the observatory was transferred to the New Jersey Institute of Technology (NJIT) in 1997. Funding comes from NASA, the National Science Foundation, the United States Air Force, and other agencies.

The location at Big Bear Lake is optimal due to the clarity of the sky and the presence of a body of water. The lake surface is about 2,055 meters (6,742 ft) above sea level, putting it above a significant portion of the atmosphere. The main observatory building is in the open waters of the lake with an approximate 200 meter causeway extending south from the north shore. The water provides a cooling effect on the atmosphere surrounding the building and helps eliminate ground heat radiation waves that normally would cause optical aberrations.

When construction began in 1968, the water level of Big Bear Lake was significantly lower allowing land access to the construction site. The foundation was poured and completed just prior to the winter of 1968. In January and February 1969, three large storms caused intense flooding in central and southern California. The Los Angeles basin experienced the largest rain fall total for a two-month period since 1884. Big Bear Lake received over 70 inches of precipitation (almost 5 times the average precipitation). As a result of the flooding, the construction site was surrounded by water and the basement level of the observatory building was submerged. Barges were built to complete construction of the observatory and a causeway was constructed several years later to provide land access again.