The space shuttle Columbia, packed with telescopes and astronomers, sailed into its second day in orbit following a successful predawn launch yesterday that ended six months of delays.

Columbia lifted off at 1:49 a.m. from Kennedy Space Center in Florida, and the crew spent the day calibrating the four telescopes mounted in the shuttle cargo bay.

"It appears that all the payload systems are in good shape, and after we get through our initial calibrations, focusing and alignment . . . we're very optimistic about the prospect of some outstanding science," said mission manager Jack Jones.

The first astronomical observation was scheduled to begin early today when one of three ultraviolet telescopes was to study the light from a star known as HD37903 to measure the amount of obscuring dust in the vast reaches between the stars.

This was NASA's fifth attempt to launch the $150 million astronomy mission, called Astro-1, which had been scheduled for a May 30 liftoff. That launch and subsequent attempts were foiled by persistent hydrogen leaks that prompted NASA to ground the shuttle fleet for the summer.

The Astro-1 astronomers are working around the clock to study some of the hottest objects and most violent processes in the universe, including an unusually close exploding star, black holes and quasars. They are equipped with one X-ray telescope and three ultraviolet telescopes, which "see" wavelengths of light that are invisible to the human eye and blocked by the atmosphere from the view of ground-based telescopes.

The Astro-1 instruments are designed to supplement -- and help spot targets for -- the orbiting Hubble Space Telescope, scientists said. They also represent a kind of hands-on astronomy that is vanishing, according to some.

"These instruments were built by scientists and students, not in gleaming aerospace labs. This is how you train the instrument-builders of the future," said Astro-1 astronomer Stephen Maran, of Goddard Space Flight Center in Greenbelt.

"It's the real experience of doing astronomy in the grand and vanishing tradition. . . . These are real experimenters, coming out of their labs . . . and launching their telescopes," he said.

The crew of seven is the largest to fly since Challenger carried seven people to their deaths in January 1986. It also includes the first non-astronauts to fly since schoolteacher Christa McAuliffe and satellite engineer Gregory Jarvis perished in that accident.

The Astro crew endured the longest wait for a mission in the history of the shuttle program. The launch originally was targeted for 1986, when it was to observe Halley's comet, but was grounded after the Challenger disaster.

Columbia's commander, Vance Brand, 59, has made four shuttle flights and is now the oldest person to fly in space. The crew includes four other veterans: pilot Guy Gardner, 42, of Alexandria; Jeffrey A. Hoffman, 45, an astrophysicist; John M. "Mike" Lounge, 43, also a scientist; and Robert A.R. Parker, 53, an astronomer.

The non-astronauts, referred to as payload specialists, are Samuel T. Durrance, 46, a research scientist in the Physics and Astronomy Department at Johns Hopkins University in Baltimore, and Ronald A. Parise, 38, a senior scientist at Computer Science Corp. in Silver Spring.

Their in-flight schedule is one of the busiest ever, with the crew splitting two 12-hour shifts around the clock.

During the nine-day mission, which may be extended to 10, the astronauts are to maneuver the orbiter through some 300 attitude changes to position Columbia so that the telescopes can lock onto almost that many targets, officials said.

Observations must be interrupted whenever Columbia passes through a region known as the South Atlantic Anomaly, where Earth's radiation belts swoop closer to the planet and the shuttle's orbital path, disrupting the instruments. The launch was timed to minimize this effect. Most passes through the Anomaly will occur in the daylight portions of Columbia's orbits, while most of the astronomical observations are to be done during the part of each orbit when the shuttle is in darkness.

For the first time, Astro will enable scientists to image the same celestial object with both X-ray and ultraviolet instruments simultaneously. With all four telescopes focusing on the same approximately 200 targets, the Astro team is expected to manage about 1,000 distinct observation tasks during the mission.

Astro-1's X-ray telescope will be controlled from Goddard, while the three ultraviolet instruments are to be managed from Marshall Space Flight Center in Huntsville, Ala.

Each time the launch date slipped, even slightly, the mission's planners had to rewrite the computer files for each of the 200 or more objects to be studied, as the Earth moves around the sun and the sun obscures a different part of the sky.

"This must make about 15 or 20 times they've rewritten the mission plans," said Edward Weiler, NASA's chief scientist for Astro-1. "Luckily, the universe is a big place, and there are a lot of targets."

Jupiter, for instance, will be much more observable this week than during previous potential flight times. But the chance to observe a bright comet has faded.

The mission schedule includes a 20-minute science lesson from space, to be beamed to classrooms around the country on the fifth day.