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(meteorobs) Fw: DoD Satellite Fireball detection.
Posted with the kind permission of Dr. Peter Brown.
----- Original Message -----
From: Peter Brown <pbrown@julian.uwodot ca>
Subject: [MIAC-L] DoD fireball detection analysis and possible fall location
> Fireball Detection
>
> IR sensors aboard US DOD satellites detected the impact of a bolide
> over
> the Eastern US on 23 July 2001 at 22:19:11 UTC.
> The object was traveling roughly East to West.
> The object was first detected at an altitude of approximately 82km at
> 41.5
> North Latitude, 75.6 West Longitude,
> and tracked down to an altitude of approximately 32 km at 41.3 North,
> 77.3 West.
> The impact was simultaneously detected by space based visible wavelength
> sensors
> operated by the US Department of Energy. The total radiated energy was
> approximately 1.27 X 10^12 joules.
>
> **************************************************************************
>
> PLEASE NOTE THAT THIS SATELLITE BOLIDE RELEASE AND ALL PREVIOUS
>
> SUCH RELEASES CAN BE FOUND ON THE WWW AT
>
> http://phobos.astro.uwodot ca/~pbrown/usaf.html
>
> --
>
>
> To attempt to assist those looking for material from this object,
> the undersigned has computed a set of possible orbits, likely
> initial velocity, inferred mass and range of possible ground
> points for various sized fragments from these DoD data. It is emphasized
>
> these are approximate and preliminary.
>
> Orbit
>
> The satellite derived apparent radiant azimuth is approximately
> 80 degrees and the elevation is 21 degrees. The terminal ground
> projection of the fireball path is a ground distance of 83 km
> from the 32 km altitude position at 41.2N, 78.3W.
> Referenced to this location, the apparent radiant and a range of
> possible velocities yield the following table of low-precision
> orbital solutions:
>
> Month : 7 Day : 23 Time (UT) : 22.317
> Terminal Ground Point (projected) :
> Lat : 41.2000 Long : -78.3000
>
> at azm vel ras de sma ecct incl argp lasn aph
> per
> 21 80 12.0 302.3 -0.9 1.01 0.167 3.2 281 121.097 1.18
> 0.84318
> 21 80 13.0 295.7 5.1 1.08 0.224 6.0 267 121.097 1.33
> 0.84073
> 21 80 14.0 291.8 8.6 1.17 0.278 8.4 257 121.097 1.49
> 0.84356
> 21 80 15.0 289.1 10.9 1.27 0.333 10.4 251 121.097 1.69
> 0.84652
> 21 80 16.0 287.1 12.5 1.39 0.388 12.2 246 121.097 1.92
> 0.84878
> 21 80 17.0 285.6 13.8 1.53 0.445 13.8 242 121.097 2.21
> 0.85031
> 21 80 18.0 284.5 14.7 1.71 0.502 15.3 239 121.097 2.57
> 0.85123
> 21 80 19.0 283.5 15.5 1.94 0.562 16.7 237 121.097 3.03
> 0.85166
> 21 80 20.0 282.7 16.1 2.25 0.622 17.9 235 121.097 3.66
> 0.85171
> 21 80 21.0 282.1 16.6 2.69 0.684 19.1 233 121.097 4.54
> 0.85149
> 21 80 22.0 281.5 17.0 3.37 0.747 20.2 232 121.097 5.88
> 0.85105
> 21 80 23.0 281.1 17.4 4.51 0.812 21.3 230 121.097 8.18
> 0.85044
> 21 80 24.0 280.7 17.7 6.94 0.878 22.3 229 121.097 13.03
> 0.84971
> 21 80 25.0 280.3 18.0 15.41 0.945 23.2 229 121.097 29.98
> 0.84888
> 21 80 26.0 280.0 18.2 -61.74 1.014 24.1 228 121.097-124.33
> 0.84798
>
>
> Where at is the radiant apparent altitude, azm is the apparent azimuth,
> vel is the initial velocuty in km/s,
> ras is the right ascention of the
> geocentric radiant, de is the declination of the geocentric radiant, sma
> is the semi-major axis of the
> orbit in AU, ecct is the eccentricity, incl is the inclination, lasn is
> the longitude of the ascending node, aph
> is the aphelion distance in AU, per is the perihelion distance in AU.
> All angular elements
> are J2000.0
>
> >From these orbit solutions, the most similarity with previously
> determined meteorite orbits is found for
> initial velocities in the 17-20 km/s range, though lower velocities are
> possible.
> Note that velocities in excess of 22 km/s are unlikely and those in
> excess of 26 km/s are unbounded.
>
> >From the optical energy estimates and assuming a 10% optical conversion
> efficiency to total yield (as has been
> found to be reasonable for several previous events), the total initial
> energy for this bolide would be 1.27x10^13J
> (or 3.0 kT TNT equivalent). For a velocity of 17 km/s this represents an
> initial mass of approximately 90 metric
> tonnes; for 20 km/s it is approximately 30 metric tonnes.
>
> Fragment fall locations.
>
> The uncertainty in initial velocity (as well as velocity at the final
> end point) make estimates
> for the fall locations extremely uncertain. We can say that material
> should be located uprange
> of the terminal ground point (78.3W, 41.2N). Approximate darkflight
> computations (assuming an end velocity at
> 32 km of 12 km/s) give the following ground locations for an ordinary
> chondrite:
>
> Mass (kg) Lat (N) Long (W)
> 0.1 41.26 77.48
> 0.3 41.25 77.53
> 1 41.25 77.60
> 7 41.24 77.70
> 10 41.22 77.85
> 150 41.22 77.87
>
>
> This region is part of the Sproul State forest.
>
>
> --
> *********************************************************************
> Dr. Peter Brown
> Los Alamos National Laboratory
> Technical Area - 51, Bld 80
> Group EES-8, Earth and Environmental Sciences Division
> Mail Stop J577
> Los Alamos, New Mexico
> 87545
> USA
>
> ph:505-665-7134
>
> email:pbrown@vega.lanldot gov
>
> fax:505-667-9122
>
> ph:505-820-2480 (H)
> *********************************************************************
>
>
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