Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery and Photometric Observation of the Optical Counterpart in a
  Possible Galactic Halo X-ray Transient, XTE J1118+480   We discovered the optical counterpart about 13 mag of a soft X-ray transient,
XTE J1118+480 on 2000 March 30. We perform astrometry and provide the accurate
position as R.A. = 11h18m10s.85, Decl. = +48o02'12".9. The outbursting object
is identified with a 18.8 mag star in USNO catalog. Our pre-discovery data
shows another outburst during 2000 January, again coinciding with an outburst
detected in X-rays. Through the CCD time-series photometry, we found the
presence of a periodic variation with the amplitude of 0.055 mag and the period
of 0.17078(0.00004)d which we consider as promising candidate of orbital
period. Because of the high galactic latitude and faint quiescence magnitude of
18.8, XTE J1118+480 is the possible first firmly identified black hole
candidate (BHC) X-ray transient in the galactic halo.

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The categories of this paper are: nucl-ex
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The categories of this paper are: cond-mat
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The categories of this paper are: acc-phys
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The categories of this paper are: chao-dyn
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The categories of this paper are: q-alg
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The categories of this paper are: econ
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The categories of this paper are: eess
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The categories of this paper are: funct-an
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The categories of this paper are: q-bio
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The categories of this paper are: physics
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The categories of this paper are: gr-qc
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The categories of this paper are: quant-ph
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The categories of this paper are: hep-ph
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The categories of this paper are: nlin
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The categories of this paper are: solv-int
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The categories of this paper are: chem-ph