HAWC is the High-Altitude Water Cherenkov Observatory, nestled at 14,000 feet above sea level between two mountains – Pico de Orizaba and Sierra Negra – in Mexico. It was constructed to locate sources of gamma rays by detecting the secondary particles resulting from the interaction of gamma rays in Earth’s upper atmosphere. Gamma rays are made in extreme environments in the universe, such as supernova explosions, pulsars, and supermassive black holes

HAWC uses light sensors inside 50,000-gallon water tanks to detect the secondary particles of gamma rays. As these particles travel through the water tanks, they produce faint blue light, known as Cherenkov radiation. A total of 300 tanks covers an area of about four football fields.

More than 120 scientists in Europe, Mexico, and the U.S. are involved in the HAWC collaboration.  Construction of the gamma ray observatory was completed in March 2015, and results of the first year of operation are now available. At the meeting of the American Physical Society on April 16-19, in Salt Lake City, Utah, scientists will report the first discoveries made possible by HAWC.

Among several findings to be reported at the APS meeting is the discovery of several new sources of gamma rays several thousands of light years away in our very own galaxy, the Milky Way. Discovering many new distant objects in so short a time is evidence of HAWC’s sensitivity, Taboada says. It is about 15 times as sensitive as the best previous instruments to survey the sky for gamma rays.

A unique capability of HAWC is that is operates day and night and observes a much larger fraction of the sky than is possible with other instruments, making HAWC an ideal survey detector, Taboada says. “HAWC will help us draw a fuller picture of the universe than we’ve known before.”

Construction of HAWC was funded by the National Science Foundation (NSF) and the U.S. Department of Energy and by Mexico’s Consejo Nacional de Ciencia y Tecnologia. Taboada’s HAWC research in Georgia Tech is funded by NSF and National Aeronautics and Space Administration (NASA).