The High-Altitude Water Cherenkov Gamma-Ray Observatory

HAWC Site: Parque Nacional Pico de Orizaba

The Park

Flowers at the HAWC site
Flora at the site, captured by a HAWC collaborator (© 2011).

The HAWC site is inside the Parque Nacional Pico de Orizaba, a Mexican national park. The park contains Citlaltepetl (or Pico de Orizaba), the highest peak in Mexico at 5610 meters, and Sierra Negra, a 4600-meter extinct volcano 7 km southwest of Citlaltepetl. Pico de Orizaba is a dormant volcano; its most recent eruption occurred in 1687. A relatively flat saddle point between the two peaks is the location of the detector.

The park is environmentally sensitive. Pico de Orizaba boasts one of the highest tree lines in the world at 4100 meters, and the forest on its slopes affect cloud formation and rainfall in populated areas to the south and west. The HAWC observatory is being built with this environmental sensitivity in mind. Prior to construction the site was covered only by low brush. However, it has been graded to allow for the placement of the water Cherenkov detectors, electronics trailers, and outbuildings. When the experiment has finished operations, all structures will be removed and the site will be returned to its natural state.

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Other Instruments at the Site

Thanks to the high altitude and relative accessibility of the site from the nearby cities of Puebla and Ciudad Serdán, several other scientific instruments are located in the park. By far the biggest is the Large Millimeter Telescope, a 50-meter radio dish located at the summit of Sierra Negra. HAWC has benefitted greatly from the presence of this facility, because roads, transmission lines, and network lines were placed on the mountain during the construction of the LMT.

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