Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: RXJ0123.4-7321, a Be/X-ray binary in the wing of the SMC   To confirm faint Be/X-ray binary candidates from the XMM-Newton survey of the
Small Magellanic Cloud, we searched for X-ray outbursts in archival ROSAT
observations. We found that RXJ0123.4-7321 was much brighter when detected with
ROSAT than seen 16 years later by XMM-Newton. We analysed the ROSAT
observations and the OGLE I-band light curve of the optical counterpart to
investigate the nature of the system. High long-term variability in the X-ray
flux of a factor of ~150 was found between the ROSAT and XMM-Newton detections,
indicating strong outburst activity during the ROSAT observations. The I-band
light curve reveals long-term variability and regular outbursts with a period
of (119.9+-2.5) days indicating the orbital period of the binary system. The
large X-ray flux variations and the properties of the optical counterpart
confirm RXJ0123.4-7321 as a new Be/X-ray binary in the wing of the Small
Magellanic Cloud.

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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: ao-sci
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The categories of this paper are: q-bio
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The categories of this paper are: cond-mat
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The categories of this paper are: nlin
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The categories of this paper are: mtrl-th
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The categories of this paper are: physics
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The categories of this paper are: adap-org
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: q-alg
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The categories of this paper are: hep-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: gr-qc