International Comet Quarterly

CBET 3423

                                                  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@eps.harvard.edu (alternate cbat@iau.org)
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