Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The X-Ray Position and Infrared Counterpart of the Eclipsing X-Ray
  Pulsar OAO 1657-415   We have measured the precise position of the 38-s eclipsing X-ray pulsar OAO
1657-415 with the Chandra X-Ray Observatory: RA = 17h00m48.90s, Dec =
-41d39m21.6s, equninox J2000, error radius = 0.5 arcsec. Based on the
previously measured pulsar mass function and X-ray eclipse duration, this
10.4-d high-mass X-ray binary is believed to contain a B supergiant companion.
Deep optical imaging of the field did not detect any stars at the Chandra
source position, setting a limit of V>23. However, near-IR imaging revealed a
relatively bright star (J=14.1, H=11.9, K_s=10.7) coincident with the Chandra
position, and we identify this star as the IR counterpart of OAO 1657-415. The
IR colors and magnitudes and the optical non-detections for this star are all
consistent with a highly reddened B supergiant (A_V= 20.4 +/- 1.3) at a
distance of 6.4 +/- 1.5 kpc. This implies an X-ray luminosity of 3e36 erg/s
(2-10 keV). IR spectroscopy can verify the spectral type of the companion and
measure its radial velocity curve, yielding a neutron star mass measurement.

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The categories of this paper are: comp-gas
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The categories of this paper are: hep-th
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The categories of this paper are: mtrl-th
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: dg-ga
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The categories of this paper are: atom-ph
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The categories of this paper are: solv-int
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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: adap-org
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The categories of this paper are: hep-ph
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The categories of this paper are: acc-phys
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The categories of this paper are: quant-ph
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The categories of this paper are: chem-ph
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The categories of this paper are: hep-ex