A Nation-Wide Research Facility

Although it is considered one observatory, the U.S. National Science Foundation Laser Interferometer Gravitational-wave Observatory laboratory comprises four facilities across the United States: two gravitational wave detectors (the interferometers) and two university research centers. The interferometers are situated 3,002 km (1,865 miles) apart, in Washington State (LIGO Hanford) and Louisiana (LIGO Livingston). The two primary research centers are located at the California Institute of Technology (Caltech) in Pasadena, California, and the Massachusetts Institute of Technology (MIT) in Cambridge, Massachusetts.

LIGO Livingston corner station

LIGO Livingston's corner station. Each arm extends 4 km (2.5 mi.) from this building. (Credit: Caltech/MIT/LIGO Lab/W. Katzman)

LIGO Hanford site

LIGO Hanford's X-arm stretches off into the Washington desert. (Credit: Kim Fetrow)

Hanford WA and Livingston LA are home to the two interferometers that make NSF LIGO an "observatory". About 40 people work full-time at each site, including engineers, technicians, scientists, education and public outreach staff, and administrative and business personnel.

When observing, each detector collects its own data, which is compared in real time with that streaming from the other detector. Though this simultaneous observing is ideal for confirming gravitational wave (GW) detections, it is not necessary for detecting GWs, and sometimes the detectors work alone if, for example, weather or technical conditions preclude one from operating. Ultimately, operating in a coordinated manner is best for LIGO's ability to verify a gravitational-wave detection, and it was a critical part of confirming the world's first detection of gravitational waves emitted by two colliding black holes 1.3 billion light years away. Today, LIGO's computers are good enough at recognizing gravitational wave signals that single-detector detections have become routine.

As major academic and research institutions with world-class laboratories and facilities, Caltech and MIT are the home bases for many LIGO engineers who research and test ways to improve LIGO's sensitivity and stability, and the physicists and astrophysicists who strive to understand the properties of the phenomena that generate gravitational waves. These critical tasks are ongoing and always evolving as LIGO and other astronomers and scientists continue to learn about and refine our understanding of the universe.

To find out why having two detectors is important to LIGO's success, visit LIGO's Dual Detectors.