Johns Hopkins Gazette: March 27, 1995

Exhausted and Exhilarated, HUT Team Digging Into Data

By Emil Venere

     Now that the Astro-2 mission has come to an exciting
conclusion, the scientific intrigue is just beginning, as Hopkins
astronomers face a new kind of pressure.

     A special session on Astro-2 findings has been scheduled for
a meeting of the American Astronomical Society in June. 

     But before the Hopkins team can even begin preparing their
presentations, they have to wade through the mountain of data
collected by the Hopkins Ultraviolet Telescope.

     Members of the HUT team said they are excited with
anticipation about what they hope to learn from the observations,
but they aren't making any predictions.

     "A huge amount of work has to go into this to get it right,"
said Arthur Davidsen, an astrophysicist who heads the Hopkins
Ultraviolet Telescope project.

     The observatory was operated within the payload bay of the
space shuttle Endeavour during a record 16 and a half day mission
that ended March 18. After returning to Hopkins, exhausted
scientists took a few days off before hitting their computer

     "I was pretty beat when I got back," said Dr. Davidsen, a
professor in the Department of Physics and Astronomy. He slept
only about three hours each night of the mission.

     One thing is certain: the hard work paid off. HUT's data are
high quality, promising to yield valuable information about the
astronomical targets observed by the orbiting telescope, said
Gerard Kriss, HUT's project scientist.

     By using a spectrograph to study ultraviolet light,
astronomers can learn many details, such as composition,
temperature and velocity of objects. HUT detected a range of
light called the far ultraviolet spectrum, which is not visible
to other telescopes and enables observations of some of the most
energetic phenomena in space.

     But astronomers can't begin writing about their findings
until the data are put through a complex series of conversions so
that they can be interpreted. The data also have to be corrected
for interference caused by radiation, called "airglow," from
Earth's upper atmosphere.

     HUT collected about 30 compact discs' worth of information--
a massive amount of data considering that an encyclopedia can fit
on one CD.

     "It's clearly a treasure trove of information," said William
Blair, another astrophysicist on the project.

     NASA has provided enough money for two and a half years of
data analysis, Dr. Kriss said. But the project has produced
enough material to keep scientists busy for a decade. HUT
astronomers collected four to five times as much data as they did
with Astro-1, which flew aboard the space shuttle Columbia in

     Chief among HUT research is the search for an "intergalactic
medium" of helium and hydrogen, presumably produced in the Big
Bang. HUT astronomers were successful in collecting data that
could prove critical in efforts to find out whether such material
really exists and, if it does, to calculate how much is present.

     "Although there's a lot of work ahead, this is the fun part,
finding out what it all means," Dr. Blair said.

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