Fireball characteristics derivable from acoustic data. (arXiv:2102.06574v1 [astro-ph.EP])
<a href="http://arxiv.org/find/astro-ph/1/au:+McFadden_L/0/1/0/all/0/1">Luke McFadden</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Brown_P/0/1/0/all/0/1">Peter Brown</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Vida_D/0/1/0/all/0/1">Denis Vida</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spurny_P/0/1/0/all/0/1">Pavel Spurn&#xfd;</a>

Near field acoustical signals from fireballs (ranges<200 km), when detected
by dense ground networks, may be used to estimate the orientation of the
trajectory of a fireball (Pujol et al., 2005) as well as fragmentation
locations (Kalenda et al., 2014; Edwards and Hildebrand, 2004). Distinguishing
ballistic arrivals (from the cylindrical shock of the fireball)from
fragmentation generated signals (quasi-spherical sources) remains a challenge,
but are obtainable through analysis of the acoustic path and the timing
observed at ground instruments. Here we describe an integrated computer code,
termed the Bolide Acoustic Modelling program or BAM, to estimate fireball
trajectories and energetics. We develop a new methodology for measuring energy
release from bolide fragmentation episodes solely from acoustic measurements
and incorporate this into BAM. We also explore the sensitivity of
seismo-acoustic fireball solutions and energy estimates to uncertainty in the
underlying atmospheric model. Applying BAM to the Stubenberg meteorite
producing fireball, we find the total fireball energy from ballistic arrivals
to be approximately $5 times 10^{10}$J which compares favorably to the optical
estimate of $4.36 times 10^{10}$J. The combined fragmentation energy of the
Stubenberg event from acoustic data was found to be $1.47^{+0.28}_{-0.12}
times 10^{10}$J, roughly one third of the ballistic or optical total energy.
We also show that measuring fireball velocities from acoustic data alone is
very challenging but may be possible for slow, deeply penetrating fireballs
with shallow entry angles occurring over dense seismic/infrasound networks.

Near field acoustical signals from fireballs (ranges<200 km), when detected
by dense ground networks, may be used to estimate the orientation of the
trajectory of a fireball (Pujol et al., 2005) as well as fragmentation
locations (Kalenda et al., 2014; Edwards and Hildebrand, 2004). Distinguishing
ballistic arrivals (from the cylindrical shock of the fireball)from
fragmentation generated signals (quasi-spherical sources) remains a challenge,
but are obtainable through analysis of the acoustic path and the timing
observed at ground instruments. Here we describe an integrated computer code,
termed the Bolide Acoustic Modelling program or BAM, to estimate fireball
trajectories and energetics. We develop a new methodology for measuring energy
release from bolide fragmentation episodes solely from acoustic measurements
and incorporate this into BAM. We also explore the sensitivity of
seismo-acoustic fireball solutions and energy estimates to uncertainty in the
underlying atmospheric model. Applying BAM to the Stubenberg meteorite
producing fireball, we find the total fireball energy from ballistic arrivals
to be approximately $5 times 10^{10}$J which compares favorably to the optical
estimate of $4.36 times 10^{10}$J. The combined fragmentation energy of the
Stubenberg event from acoustic data was found to be $1.47^{+0.28}_{-0.12}
times 10^{10}$J, roughly one third of the ballistic or optical total energy.
We also show that measuring fireball velocities from acoustic data alone is
very challenging but may be possible for slow, deeply penetrating fireballs
with shallow entry angles occurring over dense seismic/infrasound networks.

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