Amado, AZ- Today, the world of astronomy meets the science fiction world of
Isaac Asimov’s “I, Robot” with the commissioning of a new robotic
telescope. While it lacks the humanoid qualities of the movie version,
this robot will aid in humanity’s quest to understand the early universe
by observing the most distant and powerful explosions known.
Located at the Fred L. Whipple Observatory on Mt. Hopkins, Arizona, the
Peters Automated Infrared Imaging Telescope (PAIRITEL) is the first fully
“robotic” infrared telescope in North America dedicated to observing
transient astronomical events. The telescope, used for several years in a
major all-sky survey (2MASS), has been refurbished to work autonomously. It
will operate in tandem with NASA’s new gamma-ray burst satellite “Swift,”
to be launched on November 8 from Kennedy Space Center.
With PAIRITEL, a team of astronomers led by Dr. Joshua Bloom of the Harvard
Society of Fellows, Harvard-Smithsonian Center for Astrophysics (CfA) and
UC Berkeley, hopes to pinpoint the gamma-ray burst explosions from the
first and most distant stars in the universe. A gamma ray burst (GRB) is a
quick flash of gamma-ray radiation lasting about a minute, accompanied by
an afterglow emission of X-rays, visible, infrared, and radio light. The
afterglow may be observable for days to weeks afterward. The majority of
GRBs are believed to be due to massive stars that explode violently and
release tremendous blasts of energy.
“Innovatively exploring the night sky in the time domain – seeing how
things change from night to night, and even from minute to minute – is the
next big frontier in astronomy,” said Bloom. “PAIRITEL was optimized to
study cosmic events like GRBs that are here today and gone tomorrow.”
Peering back to a time when the universe was less than 1 billion years old
is the holy grail of observational astronomy. So far, only energetic galaxy
cores known as quasars have been used to probe the early universe. But
gamma-ray burst afterglows, if astronomers are able to image them quickly,
hold clear advantages over quasars. For up to one hour after the burst,
afterglow brightnesses can reach up to 1000 times that of the brightest
known quasar in the universe.
Also, explained Bloom, “The stars that create GRBs likely formed before the
black holes that create quasars. So by looking for the youngest and most
distant GRBs, we can study the earliest epochs of the universe.”
A key feature of PAIRITEL that will allow the location of distant GRBs is
its rapid response time. PAIRITEL will receive signals from Swift and
automatically move, in under 2 minutes, to the part of the sky where a GRB
has appeared.
“My ultimate vision is to have astronomy robots talking to robots, deciding
what to observe and how, with no human intervention,” said Bloom. “As it
is, PAIRITEL only e-mails us when it’s found a particularly interesting
source, or when something goes wrong and it needs help!”
Another key feature of PAIRITEL is its sensitivity at infrared wavelengths,
setting this system apart from the bevy of visible-light robotic telescopes
already in existence. Images taken with infrared filters (about twice the
wavelength of visible light) are indispensable: visible light emitted from
more than 12 billion light-years away is completely extinguished for
observers on Earth. Bloom explained, “Forget about the dimming due to the
extreme distances: the hydrogen gas between us and the explosions makes it
like searching for a firefly behind a thick London fog. In the infrared we
can peer through the shroud to the good stuff.” In addition, the unique
camera on PAIRITEL takes pictures simultaneously at three different
wavelengths of light, allowing for instantaneous full-color snapshots.
The Swift spacecraft will find GRBs at a rate 10 to 20 times higher than
currently feasible, and should find more bursts in 6 months than all
well-studied bursts to date. Bloom said he is most excited about using
Swift and PAIRITEL “together to find the golden needle in the haystack – a
high-redshift GRB that’s farther away than the most distant known galaxy or
quasar.”
When PAIRITEL is not chasing down GRBs, it will be used to make precision
measurements of supernovae to help determine the few fundamental parameters
that dictate the expansion of the universe. Among other projects, Dr.
Michael Pahre (CfA) will use PAIRITEL to study the near-infrared light of
nearby galaxies to compare it with mid-infrared light in images obtained
with NASA’s Spitzer Space Telescope. Harvard graduate student Cullen Blake,
who has written software for the project, will also use PAIRITEL to try to
find Earth-mass planets around brown dwarfs.
Other PAIRITEL team members include: Prof. Mike Skrutskie (Univ. of
Virginia), Dr. Andrew Szentgyorgyi (CfA), Prof. Robert Kirshner (Harvard
University/CfA), Dr. Emilio Falco (CfA), Dr. Thomas Matheson (NOAO), and
Dan Starr (Gemini Observatory, Hawaii). The staff of Mt. Hopkins – Wayne
Peters, Bob Hutchins, and Ted Groner – worked on the automation of the
telescope.
PAIRITEL, nearly 2 years after the inception of the project, is being
dedicated today to the late Jim Peters, who worked for the Smithsonian
Astrophysical Observatory, first on satellite tracking and then as a
telescope operator on Mt. Hopkins for 25 years. His widow and son will be
in attendance at the ceremony.
The project was funded by a grant from the Harvard Milton Fund. The
telescope is owned by the Smithsonian Astrophysical Observatory and the
infrared camera is on loan from the University of Virginia.
Additional information about Swift and PAIRITEL is available online at:
Headquartered in Cambridge, Mass., the Harvard-Smithsonian Center for
Astrophysics (CfA) is a joint collaboration between the Smithsonian
Astrophysical Observatory and the Harvard College Observatory. CfA
scientists, organized into six research divisions, study the origin,
evolution and ultimate fate of the universe.
