Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Simultaneous radio and X-ray observations of the low-mass X-ray binary
  GX 13+1   We present the results of two simultaneous X-ray/radio observations of the
low-mass X-ray binary GX 13+1, performed in July/August 1999 with the Rossi
X-ray Timing Explorer and the Very Large Array. In X-rays the source was
observed in two distinct spectral states; a soft state, which had a
corresponding 6 cm flux density of ~0.25 mJy, and a hard state, which was much
brighter at 1.3-7.2 mJy. For the radio bright observation we measured a delay
between changes in the X-ray spectral hardness and the radio brightness of ~40
minutes, similar to what has been found in the micro-quasar GRS 1915+105. We
compare our results with those of GRS 1915+105 and the atoll/Z-type neutron
star X-ray binaries. Although it has some properties that do not match with
either atoll or Z sources, GX 13+1 seems more similar to the Z sources.

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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: hep-ph
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The categories of this paper are: funct-an
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The categories of this paper are: stat
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The categories of this paper are: quant-ph
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The categories of this paper are: cs
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The categories of this paper are: hep-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-th
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The categories of this paper are: physics
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The categories of this paper are: hep-lat
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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: plasm-ph