An extensive-air-shower-like event registered with the TUS orbital detector. (arXiv:1907.06028v1 [astro-ph.HE])

An extensive-air-shower-like event registered with the TUS orbital detector. (arXiv:1907.06028v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Garipov_G/0/1/0/all/0/1">G.K. Garipov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaznacheeva_M/0/1/0/all/0/1">M.A. Kaznacheeva</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Khrenov_B/0/1/0/all/0/1">B.A. Khrenov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Klimov_P/0/1/0/all/0/1">P.A. Klimov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Panasyuk_M/0/1/0/all/0/1">M.I. Panasyuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Petrov_V/0/1/0/all/0/1">V.L. Petrov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sharakin_S/0/1/0/all/0/1">S.A. Sharakin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shirokov_A/0/1/0/all/0/1">A.V. Shirokov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yashin_I/0/1/0/all/0/1">I.V. Yashin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zotov_M/0/1/0/all/0/1">M.Yu. Zotov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grinyuk_A/0/1/0/all/0/1">A.A. Grinyuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Grebenyuk_V/0/1/0/all/0/1">V.M. Grebenyuk</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lavrova_M/0/1/0/all/0/1">M.V. Lavrova</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tkachev_L/0/1/0/all/0/1">L.G. Tkachev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tkachenko_A/0/1/0/all/0/1">A.V. Tkachenko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saprykin_O/0/1/0/all/0/1">O.A. Saprykin</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Botvinko_A/0/1/0/all/0/1">A.A. Botvinko</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Senkovsky_A/0/1/0/all/0/1">A.N. Senkovsky</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Puchkov_A/0/1/0/all/0/1">A.E. Puchkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bertaina_M/0/1/0/all/0/1">M. Bertaina</a>

TUS (Tracking Ultraviolet Set-up) is the world’s first orbital detector of
ultra-high-energy cosmic rays (UHECRs). It was launched into orbit on 28th
April 2016 as a part of the scientific payload of the Lomonosov satellite. The
main aim of the mission was to test the technique of measuring the ultraviolet
fluorescence and Cherenkov radiation of extensive air showers (EASs) generated
by primary cosmic rays with energies above ~100 EeV in the Earth atmosphere
from space. During its operation period, TUS registered almost 80,000 events
with a few of them satisfying conditions anticipated for EASs initiated by
UHECRs. Here we discuss an event registered on 3rd October 2016. The event was
measured in perfect observation conditions as an ultraviolet track in the
nocturnal atmosphere of the Earth, with the kinematics and the light curve
similar to those expected from an EAS. A reconstruction of the arrival
direction and energy of a primary particle gave the zenith angle around
$44^circ$ and the energy of the primary particle ~1000 EeV. The extreme energy
clearly is not compatible with the cosmic ray energy spectrum obtained with
ground-based experiments. We discuss all conditions of registering the event,
explain the reconstruction procedure and its limitations in details and comment
on possible astrophysical and anthropogenic sources of the signal. We believe
the measurement is important for the future missions KLYPVE-EUSO and POEMMA,
aimed for studying UHECRs from space.

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