Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: 2S1553-542: a Be/X-ray binary pulsar on the far side of the Galaxy   We report the results of a comprehensive analysis of X-ray (Chandra and Swift
observatories), optical (Southern African Large Telescope, SALT) and
near-infrared (the VVV survey) observations of the Be/X-ray binary pulsar
2S1553-542. Accurate coordinates for the X-ray source are determined and are
used to identify the faint optical/infrared counterpart for the first time.
Using VVV and SALTICAM photometry, we have constructed the spectral energy
distribution (SED) for this star and found a moderate NIR excess that is
typical for Be stars and arises due to the presence of circumstellar material
(disk). A comparison of the SED with those of known Be/X-ray binaries has
allowed us to estimate the spectral type of the companion star as B1-2V and the
distance to the system as $>15$ kpc. This distance estimation is supported by
the X-ray data and makes 2S1553-542 one of the most distant X-ray binaries
within the Milky Way, residing on the far side in the Scutum-Centaurus arm or
even further.

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The categories of this paper are: hep-th
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The categories of this paper are: q-fin
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The categories of this paper are: ao-sci
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The categories of this paper are: acc-phys
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The categories of this paper are: q-alg
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: gr-qc
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The categories of this paper are: math
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The categories of this paper are: hep-lat
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The categories of this paper are: stat
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-bio
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The categories of this paper are: dg-ga