It was a sort of homecoming for Johns Hopkins University astronomer Arthur F. Davidsen. Only in this case, "home" was a billion light-years away.
At 6:40 p.m. yesterday, after sweating through more technical difficulties, astronauts aboard the space shuttle Columbia turned the Hopkins Ultraviolet Telescope toward a brilliant object in the constellation Virgo known only as 3C273.
The object, the brightest quasar in the sky, is more than a billion light-years beyond the outer edge of our Milky Way galaxy. But it shines with the luminosity of 100 million suns.
Scientists suspect the quasar is fueled by a super-massive black hole at the center of a large galaxy. They think the quasar's enormous energy is generated by the destruction of stars as they are swept into the black hole like soap into a tub drain.
Seventeen years ago, Davidsen sent a small ultraviolet telescope to the edge of space aboard a sub-orbital rocket to look for 3C273, and he became the first astronomer on the planet to observe a quasar -- or anything else outside our galaxy -- in the ultraviolet.
He glimpsed the quasar for only 250 seconds before the rocket fell back to Earth.
But the feat won Davidsen the Helen B. Warner Prize in 1979, astronomy's equivalent of the Nobel Prize.
Davidsen had worked ever since then to build and launch the Hopkins Ultraviolet Telescope to get another, much longer look at 3C273. His triumph came yesterday at the Marshall Space Flight Center in Huntsville, Ala., after a nervous wait for the shuttle to emerge from a routine communications blackout.
"We couldn't watch them, and we couldn't help them identify the star pattern they saw," Davidsen recalled. "It was a very tense moment."
"We were waiting anxiously for them to come back into contact. When they did, the first word we heard was, 'We found it. . . . And we're getting good data.'"
He continued to gather good data for 30 minutes -- seven times longer than his 1977 observation. "I finally felt the adrenalin that had been in my system for the last five or six days drain out of me," he said.
It was an important accomplishment. First, ultraviolet light is ideal for studying the interior structure and behavior of very hot, very violent objects such as quasars. But because both Earth's atmosphere and interstellar gases absorb ultraviolet radiation, observing quasars in ultraviolet is difficult.
Only because HUT is outside Earth's atmosphere, and because 3C273 is so close, at "only" 1 billion light-years, was Davidsen successful.
His observations promise to provide astronomers with a great deal more information about the nature and origins of quasars and the universe itself than they've ever had to work with before.