Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gamma-ray Astronomy   The relevance of gamma-ray astronomy to the search for the origin of the
galactic and, to a lesser extent, the ultra-high-energy cosmic rays has long
been recognised. The current renaissance in the TeV gamma-ray field has
resulted in a wealth of new data on galactic and extragalactic particle
accelerators, and almost all the new results in this field were presented at
the recent International Cosmic Ray Conference (ICRC). Here I summarise the 175
papers submitted on the topic of gamma-ray astronomy to the 30th ICRC in
Merida, Mexico in July 2007.

13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
9
The categories of this paper are: nlin
10
The categories of this paper are: q-bio
21
The categories of this paper are: adap-org
7
The categories of this paper are: hep-th
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg