Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: MAGIC observations of the giant radio galaxy M87 in a low emission state
  between 2005 and 2007   We present the results of a long M87 monitoring campaign in very high energy
$\gamma$-rays with the MAGIC-I Cherenkov telescope. A total of 150 hours of
data was gathered between 2005 and 2007. No flaring activity was found during
that time. Nevertheless, we have found an apparently steady and weak signal at
the level of $7\sigma$. We present the spectrum between 100 GeV and 2 TeV,
which is consistent with a simple power law with a spectral index
$-2.21\pm0.21$ and a flux normalization (at 300 GeV) of $5.4\pm1.1 \times
10^{-8} \frac{1}{\mathrm{TeV s m}^{2}}$. It complements well with the
previously published Fermi spectrum, covering an energy range of four orders of
magnitude without apparent change in the spectral index.

13
The categories of this paper are: quant-ph
1
The categories of this paper are: cs
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
3
The categories of this paper are: physics
15
The categories of this paper are: nucl-ex
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The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th