Firefighters guard Arizona observatory

SAFFORD, Ariz. – Firefighters stood guard around a $200 million mountaintop observatory and wrapped sheets of aluminum around summer cabins Tuesday to protect them from an approaching wildfire.

The flames were less than two miles from Turkey Flat, a community of 74 cabins on the side of Mount Graham. Officials said the fire could spread quickly in the hot, dry weather, but no structures had burned as of Tuesday evening.

“This was a big active day for fire but we’re still holding our own,” said Dan Oltrogge, an incident commander for the team fighting the fire.

The lightning-sparked fire and a nearby fire on another part of the mountain in southeastern Arizona had earlier prompted evacuation of the Mount Graham International Observatory and a total of about 90 cabins in Turkey Flat and another community.

Officials said the fires combined had charred an estimated 20,700 acres. The fire closest to Turkey Flats was larger, burning 12,200 acres. Both were 10 percent contained Tuesday night.

Oltrogge said the fires had charred between 25,000 and 30,000 acres combined. He didn’t have a breakdown on the size of each fire. They were 10 percent contained.

The observatory’s eight buildings and 8 1/2 acres of pine forest on Mount Graham’s 10,470-foot Emerald Peak were surrounded by a 200-foot-wide clearing, and fire crews planned more controlled burns to expand the buffer zone. It also has a sprinkler system that officials said would be turned on if flames came within a few hundred yards.

Officials said although the observatory building would probably not burn, smoke and heat could damage its delicate instruments. The observatory, an extension of the University of Arizona, has two operating telescopes and the $120 million Large Binocular Telescope, which is under construction.