[astro] [tt] a small (few m diameter) asteroid: 2008 TC_3 to impact Earth this evening

[Amara Graps]

A first .... (and nothing dangerous) ...Combining several messages
being circulated around my work this afternoon.

Amara

From: IAUC mailing list <<mailto:quai at cfa.harvard.edu>quai at cfa.harvard.edu>
Date: October 6, 2008 15:28:35 EDT
To: <>iauc1 at boulder.swri.edu
Subject: IAUC 8990: 2008 TC_3; QY Mus [22181-2009/10-R2]

                                                  Circular No. 8990
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
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02138, U.S.A.
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edu/iau/cbat.html  ISSN 0081-0304 Phone 617-495-7440/7244/7444
(for emergency use only)


2008 TC_3
     A small asteroidal object (absolute magnitude H = 30.4,
suggesting a few meters in size) discovered by the Mt. Lemmon
Survey (observer R. A. Kowalski) on Oct. 6.28 UT at Delta = 0.0033
AU (about 1.27 the moon's distance from the earth) will enter the
earth's atmosphere over northern Sudan (according to S. Chesley,
Jet Propulsion Laboratory) around Oct. 7.115, moving east to west.
Prior to entering the atmosphere, it may be around visual mag 11.
Astrometry, orbital elements, and ephemerides are given on MPECs
2008-T50, 2008-T51, and 2008-T52.


---------- Forwarded message ----------
Date: Mon, 6 Oct 2008 12:57:05 -0700
From: David Morrison <david.morrison at nasa.gov>
To: David Morrison <david.morrison at nasa.gov>
Subject: NEO News (10/06/08) Bolide impact predicted tonight

NEO News (10/06/08) Bolide impact predicted tonight!

This is a first: a very small asteroid (or rock) has been
discovered that is on course for an impact tonight in Sudan. This
information is from various reports to posted to MPML (the Minor
Planet Mailing List at groups.yahoo.com/group/mpml/). The
impactor is only about 2 m across and will break up in the
atmosphere, with no risk to those on the ground. (If something
this size hit in the daytime, it would probably not be noticed,
but at night it should put on quite show).

Alan Harris writes that this object, with the survey-assigned
designation 8TA9D69, was discovered by the University of Arizona
Mt. Lemmon survey and will almost certainly, tonight, become the
first impacting bolide discovered before entry into the Earth's
atmosphere. Steve Chesley (JPL) reports that atmospheric entry
will occur on 2008 Oct 07 0246 UTC over northern Sudan.

Andrea Milani of the University of Pisa wrote the following:
Today the object with the provisional designation 8TA9D69 was
submitted to impact monitoring by using the normal software of
the NEODyS system, by using the observations as reported by the
MPC on the NEO Confirmation Page. Based on 26 optical
observations from 2008/10/06.278 to 2008/10/06, the probability
of impact is between 99.8% and 100%; in practice the impact can
be considered sure and is for tonight. Our computation has
already been confirmed independently by others, including the JPL
NEO Program Office (with which we consult in all relevant cases
of possible impact). The effect of this atmospheric impact will
be the release, in either a single shot or maybe a sequence of
explosions, of about 1 kiloton of energy. This means that the
damage on the ground is expected to be zero. The location of
these explosions is not easy to predict due to the atmospheric
braking effects. The only concern is that they might be
interpreted as something else, that is man-made explosions. Thus
in this case, the earlier the public worldwide is aware that this
is a natural phenomenon, which involves no risk, the better.

This is the first time an asteroid impact has been predicted, and
it reflects the increasing capability of the Spaceguard Survey.
There was one previous false alarm when, for a few hours around
Christmas 2004, it appeared that an impact by a 30-m asteroid was
possible, but this was ruled out by additional observations. The
current case, however, seems much more solid.

David Morrison
-- 
+++++++++++++++++++++++++++++++++++++++++++

NEO News (now in its fourteenth year of distribution) is an
informal compilation of news and opinion dealing with Near Earth
Objects (NEOs) and their impacts. These opinions are the
responsibility of the individual authors and do not represent the
positions of NASA, Ames Research Center, the International
Astronomical Union, or any other organization. To subscribe (or
unsubscribe) contact dmorrison at arc.nasa.gov. For additional
information, please see the website http://impact.arc.nasa.gov.
If anyone wishes to copy or redistribute original material from
these notes, fully or in part, please include this disclaimer.

======================================================================

-------------

THE FOLLOWING RELEASE WAS RECEIVED FROM THE HARVARD-SMITHSONIAN CENTER
FOR ASTROPHYSICS, IN CAMBRIDGE, MASSACHUSETTS, AND IS FORWARDED FOR
YOUR INFORMATION.  (FORWARDING DOES NOT IMPLY ENDORSEMENT BY THE
AMERICAN ASTRONOMICAL SOCIETY.)  Steve Maran, American Astronomical
Society  <mailto:steve.maran at aas.org>steve.maran at aas.org

October 6, 2008

Contact:
David Aguilar
1-617-495-7462
<mailto:daguilar at cfa.harvard.edu>daguilar at cfa.harvard.edu

Christine Pulliam
1-617-495-7463
<mailto:cpulliam at cfa.harvard.edu>cpulliam at cfa.harvard.edu

CfA Release 2008-19
For Immediate Release

BOULDER-SIZED ASTEROID WILL BURN UP IN EARTH'S ATMOSPHERE TONIGHT

A tiny asteroid discovered just hours ago at an Arizona observatory will
enter Earth's atmosphere harmlessly at approximately 10:46 p.m. Eastern time
tonight (2:46 a.m. Greenwich Mean Time). There is no danger to people or
property since the asteroid will not reach the ground. It is between 3 and
15 feet (1-5 m) in diameter and will burn up in the upper atmosphere, well
above aircraft heights. A brilliant fireball will be visible as a result.

"We want to stress that this object is not a threat," said Dr. Timothy
Spahr, director of the International Astronomical Union's Minor Planet
Center.

"We're excited since this is the first time we have issued a prediction that
an object will enter Earth's atmosphere," Spahr added. Odds are between 99.8
and 100 percent that the object will encounter Earth, according to
calculations provided by Andrea Milani of the University of Pisa.

When a meteoroid (small asteroid) enters the atmosphere, it compresses the
air in front of it. That compression heats the air, which in turn heats the
object, causing it to glow and vaporize. Once it starts to glow, the object
is called a meteor.

"A typical meteor comes from an object the size of a grain of sand,"
explained Gareth Williams of the Minor Planet Center. "This meteor will be a
real humdinger in comparison!"

The meteor is expected to be visible from eastern Africa as an extremely
bright fireball traveling rapidly across the sky from northeast to
southwest. The object is expected to enter the atmosphere over northern
Sudan at a shallow angle.

"We're eager for observations from astronomers near the asteroid's approach
path. We really hope that someone will manage to photograph it," said
Williams.

The Minor Planet Center, which is located at the Harvard-Smithsonian Center
for Astrophysics, serves as the worldwide clearinghouse for asteroid and
comet observations. It collects, checks and disseminates observations and
calculates orbits.

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.

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-- 

Amara Graps, PhD      www.amara.com
Research Scientist, Southwest Research Institute (SwRI), Boulder, Colorado
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