Astronomers Create Artificial Star

Astronomers have used a ground-based laser beam to improve the resolving power of the 55-year-old Hale telescope on California’s Palomar Mountain.

Astronomers from the California Institute of Technology, the Jet Propulsion Laboratory and the University of Chicago created an artificial star by propagating a 4-watt laser beam out from the Hale Telescope and up into the night sky.

The beam was propagated as the first step in a program to expand the fraction of sky available to the technique known as adaptive optics, which allows astronomers to correct for the fuzzy images produced by Earth’s moving atmosphere, giving them a view that often surpasses those of smaller telescopes based in space.

We have been steadily improving adaptive optics using bright natural guide stars at Palomar, said astronomer Richard Dekany of CalTech.

Although the laser beam is too faint to be seen except by observers very close to the telescope, and the guide star it creates cannot be seen with the unaided eye, it is bright enough to allow astronomers to make their adaptive-optics corrections.

Palomar currently employs the world’s fastest astronomical adaptive optics system on the 200-inch Hale instrument, astronomers said. It is able to correct for changes in the atmosphere 2,000 times per second.