Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Very High Energy Gamma-Ray Astronomy   We present a review of the current status of very high energy gamma-ray
astronomy. The development of the atmospheric Cherenkov imaging technique for
ground-based gamma-ray astronomy has led to a rapid growth in the number of
observatories. The detection of TeV gamma rays from Active Galactic Nuclei was
unexpected and is providing new insights into the emission mechanisms in the
jets. Next generation telescopes are under construction and will increase
dramatically the knowledge available at this extreme end of the cosmic
electromagnetic spectrum.

25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
19
The categories of this paper are: eess
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
17
The categories of this paper are: q-fin
29
The categories of this paper are: funct-an
14
The categories of this paper are: math-ph
9
The categories of this paper are: nlin
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ