High Altitude Water Cherenkov Experiment, Gamma ray observatory at Sierra Negra volcano, Mexico.
The High Altitude Water Cherenkov Experiment is an astronomical observatory located on the slopes of the Sierra Negra volcano in the state of Puebla, Mexico. It consists of around 300 water-filled tanks fitted with light detectors that register signals produced when cosmic particles enter the Earth's atmosphere.
The observatory opened in 2015, building on earlier detection methods that had focused on lower-energy cosmic radiation. The new setup extended the range of detectable events to the most energetic phenomena coming from distant parts of the universe.
Teams from Mexican and American universities share daily operations at this facility, making it a working example of cross-border science. Visitors can see both flags at the entrance and read bilingual signs throughout the site.
The site sits at roughly 4,100 meters (about 13,450 feet) above sea level, so visitors should plan enough time to adjust to the thin air before exploring. Warm and weatherproof clothing is necessary, and it is worth checking road and access conditions before heading up.
Unlike traditional telescopes, the tanks at this observatory face upward from the ground and work around the clock, even in daylight and cloudy weather. This means the facility never needs to wait for a clear night sky to collect data.
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