Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Timing and spectral studies of the transient X-ray pulsar GX 304-1
  during an outburst   We present the timing and spectral properties of the transient X-ray pulsar
GX 304-1 during its recent outburst in 2010 August, using observations carried
out with the Proportional Counter Array (PCA) instrument on-board the Rossi
X-ray Timing Explorer (RXTE) satellite. We detected strong intensity and energy
dependent variations in the pulse profiles during the outburst. The pulse
profile showed significant evolution over the outburst. It showed complex
structures consisting of a main peak with steps on both sides during the start
of the outburst. On some days, a sharp dip like feature was seen which
disappeared at the end of the outburst; when the profile evolved into a
sinusoidal shape. At low energies, the pulse profiles appeared complex,
consisting of multiple peaks and a narrow minimum. The amplitude of the second
brightest peak in low energies decreased with energy, and above 12 keV, the
shape of the pulse profile changed to a single broad peak with a dip like
feature. The dip had energy dependence, both in phase and in width. We detected
Quasi-periodic Oscillations (QPO) at 0.125 Hz with a harmonic. The QPO feature
had a low rms value of 2.9% and it showed a positive energy dependence up to 40
keV with the rms value increasing to 9% at 40 keV. The QPO frequency decreased
from 0.128 Hz to 0.108 Hz in 12 days. During most of the outburst, the 3-30 keV
spectrum of GX 304-1 can be well fitted with a partial covering power-law model
with a high energy cut-off and iron fluorescent line emission. For a few of the
observations carried out during the decay of the outburst, the partial covering
absorption component is found to change to single component absorption. We also
found that the partial covering and high energy cut-off parameters vary
significantly with the pulse phase.

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The categories of this paper are: acc-phys
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The categories of this paper are: ao-sci
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The categories of this paper are: cond-mat
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The categories of this paper are: hep-th
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The categories of this paper are: chao-dyn
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The categories of this paper are: nucl-th
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The categories of this paper are: patt-sol
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The categories of this paper are: supr-con
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The categories of this paper are: hep-lat
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The categories of this paper are: hep-ex
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The categories of this paper are: nucl-ex
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The categories of this paper are: cmp-lg
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The categories of this paper are: q-bio
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The categories of this paper are: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: solv-int