Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The atmospheric transparency measured with a LIDAR system at the
  Telescope Array experiment   An atmospheric transparency was measured using a LIDAR with a pulsed UV laser
(355nm) at the observation site of Telescope Array in Utah, USA. The
measurement at night for two years in $2007\sim 2009$ revealed that the
extinction coefficient by aerosol at the ground level is
$0.033^{+0.016}_{-0.012} \rm km^{-1}$ and the vertical aerosol optical depth at
5km above the ground is $0.035^{+0.019}_{-0.013}$. A model of the altitudinal
aerosol distribution was built based on these measurements for the analysis of
atmospheric attenuation of the fluorescence light generated by ultra high
energy cosmic rays.

35
The categories of this paper are: mtrl-th
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
32
The categories of this paper are: atom-ph
34
The categories of this paper are: chem-ph
36
The categories of this paper are: cmp-lg
0
The categories of this paper are: hep-ph
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
31
The categories of this paper are: ao-sci
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
11
The categories of this paper are: hep-lat