Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The Hamburg Quasar Monitoring Program (HQM) at Calar Alto III.
  Lightcurves of optically violent variable sources   HQM is an optical broad-band photometric monitoring program carried out since
September 1988. We use a CCD camera at the MPIA 1.2$\,$m telescope. Fully
automatic photometric reduction relative to stars in the frames is done within
a few minutes after each exposure, thus interesting brightness changes can be
followed in detail. The typical photometric error is 1--2\,\% for a 17.5\,mag
quasar. We here present lightcurves of 14 known violently variable sources and
compare them with literature data. For two BL\,Lac objects, 1E\,1229+645 and
4C\,56.27 (1823+568), this paper is the first variability study. We have also
carried out POSS photometry to obtain indications for variability on a longer
timescale.

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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-lat
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: solv-int
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The categories of this paper are: alg-geom
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The categories of this paper are: supr-con
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The categories of this paper are: cs
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The categories of this paper are: cmp-lg
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The categories of this paper are: math
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The categories of this paper are: bayes-an
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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex