Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: X-raying Active Galaxies Found and Missed by the Sloan Digital Sky
  Survey   Current X-ray observatories, archival X-ray data, and the Sloan Digital Sky
Survey (SDSS) represent a powerful combination for addressing key questions
about active galactic nuclei (AGN). We describe a few selected issues at the
forefront of X-ray AGN research and the relevance of the SDSS to them. Bulk
X-ray/SDSS AGN investigations, X-ray weak AGN, red AGN, hard X-ray selected
AGN, high-redshift AGN demography, and future prospects are all briefly
discussed.

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The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
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The categories of this paper are: eess
3
The categories of this paper are: physics
5
The categories of this paper are: gr-qc
33
The categories of this paper are: plasm-ph
27
The categories of this paper are: comp-gas
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph