Short answers, pulled from the story.
CACTUS, short for Converted Atmospheric Cherenkov Telescope Using Solar-2, was a ground-based Air Cherenkov Telescope located outside Daggett, California, near Barstow. It was an observatory created from a former solar power plant.
CACTUS was created by converting Solar Two, a solar power plant outside Daggett, California, into an observatory. The conversion began in 2001.
The first astronomical observations at CACTUS started in the fall of 2004. Its last observing runs took place in November 2005.
CACTUS shut down because funds for observational operations from the National Science Foundation were no longer available. Without that support, observing ended after November 2005.
CACTUS was operated by the University of California, Davis. The facility was owned by Southern California Edison.
The CACTUS facility was demolished in 2009.