Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: WeCAPP - The Wendelstein Calar Alto Pixellensing Project I Tracing Dark
  and Bright Matter in M31   We present WeCAPP, a long term monitoring project searching for microlensing
events towards M 31. Since 1997 the bulge of M 31 was monitored in two
different wavebands with the Wendelstein 0.8 m telescope. In 1999 we extended
our observations to the Calar Alto 1.23 m telescope. Observing simultaneously
at these two sites we obtained a time coverage of 53 % during the observability
of M 31. To check thousands of frames for variability of unresolved sources, we
used the optimal image subtraction method (OIS) by Alard & Lupton (1998) This
enabled us to minimize the residuals in the difference image analysis (DIA) and
to detect variable sources with amplitudes at the photon noise level. Thus we
can detect microlensing events with corresponding amplifications A > 10 of red
clump giants with M_I = 0.

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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
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The categories of this paper are: hep-th
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cs
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The categories of this paper are: supr-con
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The categories of this paper are: math-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-ex
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The categories of this paper are: stat
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The categories of this paper are: adap-org
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The categories of this paper are: plasm-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin