After receiving its first fresh, full coat of paint in more than 40 years, Arecibo Observatory made its first observation in more than six months at 6:36 a.m., Saturday, Dec. 8.

The giant paint job was critical for ensuring the observatory's safety and structural integrity.

The telescope focused on the asteroid 3200 Phaethon, which travels closer to the sun than any other numbered asteroid -- about twice as close to the sun as the planet Mercury. Phaethon is the source of the Geminid meteor shower, which causes streams of shooting stars every December.

Jean-Luc Margot, Cornell assistant professor of astronomy, and Jon Giorgini of the NASA Jet Propulsion Laboratory (JPL), Pasadena, Calif., are studying Phaethon and other asteroids that have trajectories strongly affected by sunlight, sun shape and general relativity effects. Mike Nolan, an Arecibo staff scientist, conducted the Dec. 8 observation; Lance Benner of JPL leads the radar investigation of Phaethon.

Asteroid orbits are influenced by the absorption and re-emission of solar energy -- or the so-called Yarkovsky effect. These changes to the asteroidal motion will be quantified with the Arecibo radar measurements to understand the properties of near-Earth asteroids. This is one of dozens of projects now under way at the observatory.

The six-month painting project -- the first time the Arecibo platform and focal-point structure has received a thorough painting -- ended in November. Since then a skeletal crew of observatory staff worked around-the-clock to bring the 1,000-foot radio telescope and the planetary radar back to astronomical life.

Now the observatory is fully functional, with all motion, electronic, transmitting and receiving, and computing systems operating.

"It is ready to return to the task of carrying out the scientific observations for the many thousands of hours of approved research programs that will keep the telescope very busy for the next several years," said Robert Brown, director of the National Astronomy and Ionosphere Center, a national research center operated by Cornell under a cooperative agreement with the National Science Foundation.