Astronomers in Arizona say their work is being hampered by light pollution from an unexpected source -- the drug war and smuggling along the U.S.-Mexico border.

Astronomers at the Fred Lawrence Whipple Observatory near Mount Hopkins sometimes see drug smugglers and illegal immigrants making their way north through the surrounding rough, wooded terrain. They say it's not the outlaws that affect their work as much as the authorities who pursue them, The New York Times reported Friday.

A Border Patrol helicopter shining a blinding beam of light on a group of suspects at night runs the risk of interfering with the four massive telescopes as astronomers attempt to make their observations.

"It's happened," observatory spokesmen Dan Brocious said.

The mountaintop Whipple observatory has been operated jointly by the Smithsonian Institution and Harvard University since 1968.

Border Patrol checkpoints around southern Arizona, complete with high-powered beams to light them up at night, have been another sore point with astronomers. The lights are among the brightest sources of light visible at night in the area, they say.

Since the Whipple observatory was built in the Coronado National Forest, retirement communities, shopping malls and other developments have cropped up in the area, all adding to the light detected by astronomers attempting to investigate the heavens.

"When these observatories were selected, there was hardly anyone living here," Brocious said. "Tucson was a sleepy little cow town back then. There's nothing sleepy about it now."