Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Effect of intergalactic absorption in the TeV gamma-ray spectrum of Mkn
  501   We discuss an effect of the intergalactic absorption of the TeV gamma-rays in
time-averaged spectrum of Mkn 501 measured by the HEGRA Collaboration. Analysis
of the spectral behavior, variability time scale and relevant calculations of
TeV gamma-ray emission allow to conclude the presence of a noticeable
absorption of the TeV gamma-rays in the Mkn 501 energy spectrum.

15
The categories of this paper are: nucl-ex
23
The categories of this paper are: solv-int
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
5
The categories of this paper are: gr-qc
20
The categories of this paper are: acc-phys
35
The categories of this paper are: mtrl-th
31
The categories of this paper are: ao-sci
33
The categories of this paper are: plasm-ph
22
The categories of this paper are: chao-dyn
0
The categories of this paper are: hep-ph
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph