LBT Captures Extremely Faint Light With Its First Mirror and Camera(Forwarded)

University Communications
University of Arizona
Tucson, Arizona

Contact Information:

Xiaohui Fan
520-626-7558
http://sancerre.as.arizona.edu/~fan/

John M. Hill
Technical Director, LBT Observatory
520-621-3940
http://abell.as.arizona.edu/~hill/

Richard F. Green
Director, LBT Observatory
520-626-7088

March 12, 2007

LBT Captures Extremely Faint Light With Its First Mirror and Camera
By Lori Stiles

It was a small, barely visible glow among a myriad brighter stars and
galaxies in the night sky.

But to astronomers who recorded the faint light with the Large Binocular
Telescope (LBT) on Feb. 21, it was gratifying proof that the first
8.4-meter mirror and camera on what soon will be the world's most powerful
telescope -- the twin-mirrored telescope on Mount Graham, Ariz. --
delivers science as promised.

University of Notre Dame astronomer Peter Garnavich headed an
international team of observers who with the LBT's first primary mirror
and its "blue" camera captured a data point on the light curve of the
optical afterglow from a gamma ray burst that exploded almost a month
earlier.

The observation is a milestone -- the LBT Observatory's first published
scientific result. The result was reported in an online newsletter for
scientists who study gamma ray bursts, which are very short-lived
phenomena.

Only an 8-meter class telescope can see such very faint light from a
26th-magnitude object, or a hundred million times fainter than can be seen
with the unaided eye, said Xiaohui Fan of the University of Arizona's
Steward Observatory, a member of the observing team. Optical light from
the afterglow of the Jan. 25 gamma ray burst came from about 10 billion
light years away.

"The LBT is now going deep into the sky and getting data of the good
quality that we thought we would get," Fan said. "Even with an 8-meter
telescope, it takes about a half hour to gather light on an object that
faint. From the telescope technical point of view, this is good news for
us just because the accuracy of this measurement is very close to what was
actually predicted this system could deliver. The system is working fine."

The team took 10 "dithered" 200 second exposures instead of a single 2,000
second exposure for the observation. The dithering technique moved the
telescope slightly between 10 individual, 200-second exposures to cut down
on detector noise. Astronomers then average the results.

The observation is part of the "science demonstration" program that the
LBT began in January. A committee representing all LBT partners selected
30 programs that will demonstrate the science LBT can do. Astronomers from
partner institutions use the LBT in teams, learning to command the
telescope and sharing the risks of technical downtime. Individual
investigators will use the telescope for their specific projects later.

The Large Binocular Telescope is the first of the next generation of
extremely large telescopes. The telescope achieved first light with the
first of its two 8.4-meter (27.6 feet) primary mirrors on Oct. 12, 2005.
It will see "first binocular light" -- light from both huge mirrors on a
single mount -- later this year.

Located 10,500 feet high on Mount Graham in southeastern Arizona, the $120
million LBT will have a collecting area equivalent to an 11.8-meter
(39-foot) circular aperture. Combining light beams from the two primary
mirrors will give the LBT the resolution of a 22.8-meter (about 75-foot)
telescope.

The LBT is an international collaboration among institutions in the United
States, Italy and Germany. The partners a

* The University of Arizona on behalf of the Arizona university system
* Italy's Instituto Nazionale di Astrofisica
* Germany's LBT Beteiligungsgesellschaft representing the Max Planck
Institute, the Astrophysical Institute (Potsdam) and Heidelberg University
* The Ohio State University and The Research Corporation, which provides
telescope access to The University of Notre Dame, University of Minnesota
and University of Virginia

Related Web sites:

* Downloadable LBT photo
http://uanews.ccit.arizona.edu/maste...ce/sci0081.jpg
* Large Binocular Telescope
http://medusa.as.arizona.edu/lbto/
* LBT image of Jan. 25 gamma ray burst afterglow
http://www.nd.edu/~pgarnavi/grb070125/LBT_070221.jpg