More than 40 Nights of Kitt Peak Observations of NASA's Deep Impact Comet to Culminate on July 3

http://www.noao.edu/outreach/press/pr05/pr0505.html

National Optical Astronomy Observatory

FOR IMMEDIATE RELEASE: Thursday, June 23, 2005
RELEASE NO: NOAO 05-05

More than 40 Nights of Kitt Peak Observations of NASA's Deep Impact
Comet to Culminate on July 3

For More Information:

Douglas Isbell
Office of Public Affairs and Educational Outreach
National Optical Astronomy Observatory
Phone: 520/318-8230
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All of the major telescopes of the National Optical Astronomy
Observatory (NOAO) on Kitt Peak are observing comet Tempel 1 for
several
nights before and after the planned Deep Impact event. Indeed, by the
night of July 8, Kitt Peak National Observatory will have been used for
43 nights in 2005 in scientific support of the planned collision at
approximately 10:52 p.m. local time on July 3 between the icy comet and
a special probe released from the main Deep Impact spacecraft.

The coordinated observing team on Kitt Peak's major National Science
Foundation telescopes consists of Tony Farnham, Matthew Knight and Rob
Swaters from the University of Maryland, and Beatrice Mueller and Nalin
Samarasinha from the NOAO scientific staff.

The team's goal was to monitor Comet Tempel 1 on a monthly basis, with
two main purposes. "First, we need to figure out the fundamental
physical properties of the comet, so that we can provide information to
the Deep Impact mission science team that can be used in both the long-
and short-term planning of the mission," Farnham says. "By observing
Tempel 1 every month, we can determine how it changes with time, which
helps us predict what it will be doing at the time of impact. Second,
we
need to follow its behavior under normal circumstances, so that when we
observe it after the encounter, we can separate out the changes that
result from normal variations in the comet from the changes that are
caused by the impact."

Between January and June 2005, the team had a total of 24 nights of
observing time at the Kitt Peak 2.1-meter and Mayall 4-meter
telescopes.
"During these observing runs, we imaged the comet using a broadband and
several narrowband filters, which allow us to isolate the light from
different gases and from the dust," Farnham explains. "The resulting
images can be used to study the structure of the gas and dust in the
coma, as well as allowing us to use the brightness to measure how much
gas and dust is being produced. We used the images obtained between
January and May to determine many of the rotational properties of the
nucleus, and used that information to predict how the nucleus will look
to the Deep Impact spacecraft during its approach."

Around the time of impact, the team has observing time on three
different Kitt Peak telescopes: eight nights at the 4-meter telescope,
which will be used for narrowband imaging, five nights at the WIYN 3-5
meter telescope for optical spectroscopy, and seven nights at the
2.1-meter to obtain infrared images.

Mayall 4-meter telescope at Kitt Peak

On the night of impact, Farnham will be at the Mayall 4-meter telescope
taking images of the comet with narrowband filters to look for changes
in the comet after the event. Potential changes include increases in
the
amount of gas and dust that is being produced, immediate changes in the
structure of its coma (the comet's surrounding cloud of material) as
any
crater ejecta expands away from the nucleus, and any long-term changes
that occur as a result of fundamental changes on the nucleus.

Kitt Peak 2.1-meter telescope

Matthew Knight and Rob Swaters of the University of Maryland will be
observing the Deep Impact encounter with the 2.1-meter telescope using
the SQIID camera from two nights before impact until five nights after
impact. This will be a unique part of the worldwide observing campaign,
as SQIID is the only camera which will take simultaneous images in the
J, H, and K bands. Comparison of the relative fluxes in these
bandpasses
will probe the temperature evolution of the coma in the days after
impact.

Knight will have spent 18 nights observing Tempel 1 at Kitt Peak
National Observatory this year (plus eight additional nights in which
data on Tempel 1 were obtained during a different project.)

WIYN 3.5-meter telescope

Beatrice Mueller and Nalin Samarasinha of the NOAO scientific staff
will
observe at the WIYN telescope from July 2 - 6, using the Densepack
fiber
spectrograph. They expect to observe the emission lines of molecules
such as CN, C2, C3, CH, and CO+.

"We can study the relative abundances of these species and see if and
how they change. These are daughter speciesthat arise from subsequent
interactions after the material leaves the comet," Mueller says. "With
Densepack, we can sample the coma simultaneously and see if all these
lines originate from the nucleus or if some are from distributed
sources.

"Together with the University of Maryland group, we have observed the
comet every month for at least four nights per month with imaging in
broadband and narrowband filters," she adds. "The narrowband filters
are
placed where emission lines are, and so-called continuum filters
measure
in between the lines and are best for studying materials such as dust."

Astronomers are also excited about the possibility of seeing
"serendipitous emissions" from the comet of chemical species created by
the energy of the comet impact.

This group of professional astronomers will be augmented by a special
public program on Kitt Peak for 50 people during the night of the
event,
which is now sold out.

Located 55 miles southwest of Tucson, AZ, Kitt Peak National
Observatory
is part of NOAO, which is operated by the Association of Universities
for Research in Astronomy (AURA) Inc., under a cooperative agreement
with the National Science Foundation.

For more information about Deep Impact, visit the mission's Web sites
at
deepimpact.umd.edu/ and
www.nasa.gov/deepimpact .