Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Latest results of ultra-high-energy cosmic ray measurements with
  prototypes of the Fluorescence detector Array of Single-pixel Telescopes
  (FAST)   The origin and nature of ultra-high-energy cosmic rays (UHECRs) remain an
open question in astroparticle physics. Motivated by the need for an
unprecedented aperture for further advancements, the Fluorescence detector
Array of Single-pixel Telescopes (FAST) is a prospective next-generation,
ground-based UHECR observatory that aims to cover a huge area by deploying a
large array of low-cost fluorescence detectors. The full-scale FAST prototype
consists of four 20 cm photomultiplier tubes at the focus of a segmented mirror
1.6 m in diameter. Over the last five years, three prototypes have been
installed at the Telescope Array Experiment in Utah, USA, and one prototype at
the Pierre Auger Observatory in Mendoza, Argentina, commencing remote
observation of UHECRs in both hemispheres. We report on the latest results of
these FAST prototypes, including telescope calibrations, atmospheric
monitoring, ongoing electronics upgrades, development of sophisticated
reconstruction methods, and UHECR detections.

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The categories of this paper are: hep-th
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The categories of this paper are: comp-gas
33
The categories of this paper are: plasm-ph
1
The categories of this paper are: cs
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The categories of this paper are: funct-an
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The categories of this paper are: hep-lat
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The categories of this paper are: gr-qc
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The categories of this paper are: econ
31
The categories of this paper are: ao-sci
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The categories of this paper are: adap-org
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The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int