[meteorite-list] Chebarkul/Chelyabinsk - Trajectory Update - IAU release

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Mon, 25 Feb 2013 09:51:46 -0500
Message-ID: <CAKBPJW9U4n8iMKzWRSwa-=3Z_=yor0SV+oc94hgp-t6Bd-rbVQ_at_mail.gmail.com>

I'm not sure if this was posted yet or not. It was just sent to the
IAU yesterday.

Electronic Telegram No. 3423
Central Bureau for Astronomical Telegrams
INTERNATIONAL ASTRONOMICAL UNION
CBAT Director: Daniel W. E. Green; Hoffman Lab 209; Harvard University;
20 Oxford St.; Cambridge, MA 02138; U.S.A.
e-mail: cbatiau at ... (alternate cbat at ...)
URL http://www.cbat.eps.harvard.edu/index.html
Prepared using the Tamkin Foundation Computer Network


TRAJECTORY AND ORBIT OF THE CHELYABINSK SUPERBOLIDE
Jiri Borovicka, Pavel Spurny, and Lukas Shrbeny, Astronomical Institute
of the Academy of Sciences, Ondrejov, Czech Republic, report that they have
computed the atmospheric trajectory and velocity of the superbolide of 2013
Feb. 15.139 UT (3h20m UT), which caused some damage in the city of
Chelyabinsk, Russia. They used seven casual video records provisionally
calibrated with Google Maps tools. The trajectory was assumed to be linear.
The geographical coordinates of selected points along the trajectory are as
tabulated below:

Relative Longitude Latitude Height Velocity Notes
Time (s) (deg E) (deg N) (km) (km/s)

0.00 64.266 54.508 91.83 17.5 beginning of
registration
9.18 61.913 54.788 41.02 17.5 minor flare
11.20 61.455 54.836 31.73 17.5 major flare
12.36 61.159 54.867 25.81 17.5 flare
13.20 60.920 54.891 21.05 12.5 minor flare
16.20 60.606 54.922 14.94 4.3 end of
registration

The observed trajectory was 254 km long. The azimuth of the trajectory was
279.5 degrees, and the slope was 16.5 degrees to the horizontal (for the end
point). The uncertainty of the radiant is about one degree. The uncertainty
of the position of the trajectory is about 1 km (at the beginning, up to 4
km).
The pre-entry object that caused the superbolide was relatively fragile.
Severe fragmentation started at a height of 32 km under dynamic pressure of 4
MPa. The mass of the largest fragment, which landed in the lake Chebarkul,
was estimated to be 200-500 kg. One or two meteorites of the mass of several
tens of kg can be expected not far from the village Travniki. One piece of
mass approximately 1 kg may have landed to the northwest of Shchapino.
Numerous small fragments can be expected in the wide band located about 5 km
south of the trajectory, mostly between longitudes 60.9 and 61.35 degrees.
The blast wave, which strongly affected Chelyabinsk, was generated
between heights of 25 and 30 km. The radiant and heliocentric orbit were
calculated to be as follows:

Apparent radiant: Right ascension 328.6 +/- 1.0 deg
(equinox 2000.0) Declination +8.0 +/- 1.0 deg
Velocity 17.5 +/- 0.5 km/s

Geocentric radiant: Right ascension 334.7 +/- 1.2 deg
Declination -1.0 +/- 1.4 deg
Velocity 13.2 +/- 0.7 km/s

Orbit: a = 1.55 +/- 0.07 AU e = 0.50 +/- 0.02
q = 0.768 +/- 0.011 AU Q = 2.33 +/- 0.14 AU
(equinox 2000.0) Peri. = 109.7 +/- 1.8 deg Node = 326.41 deg
i = 3.6 +/- 0.7 deg

The data do not allow determination of the initial mass of the object prior
to entering the atmosphere. The trajectory will be further refined in the
future, provided that proper in situ calibrations of the videos are made.


NOTE: These 'Central Bureau Electronic Telegrams' are sometimes
superseded by text appearing later in the printed IAU Circulars.

(C) Copyright 2013 CBAT
2013 February 23 (CBET 3423) Daniel W. E. Green

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Received on Mon 25 Feb 2013 09:51:46 AM PST