Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: BeppoSAX monitoring of the ``anomalous'' X-ray pulsar 4U 0142+61   The 8.7s X-ray pulsar 4U 0142+61 was monitored by BeppoSAX between January
1997 and February 1998. This source belongs to the rapidly growing class of
"anomalous" X-ray pulsars (AXPs) which have pulse periods in the 6-12s range
and no plausible optical, infrared or radio counterparts. The BeppoSAX periods
measurements show that 4U 0142+61 continues its spin-down at a nearly constant
rate of about 2 times 10^{-12}s s^{-1}. The 0.5-10 keV pulse shape is double
peaked. The phase-averaged spectrum can be described by a steep absorbed
power-law (Gamma about 4) plus a blackbody with kT = 0.4 keV. 4U 0142+61 was
also detected serendipitously in a March 1996 RossiXTE observation pointed
towards the nearby 1455s X-ray pulsar RX J0146.9+6121. The timing analysis
results are reported for this observation and the spin history of 4U 0142+61
since 1979 is discussed.

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The categories of this paper are: hep-ph
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The categories of this paper are: eess
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The categories of this paper are: atom-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: gr-qc
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The categories of this paper are: solv-int
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The categories of this paper are: quant-ph
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The categories of this paper are: q-bio
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The categories of this paper are: q-alg
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The categories of this paper are: hep-lat
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The categories of this paper are: plasm-ph
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The categories of this paper are: nlin
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The categories of this paper are: comp-gas
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The categories of this paper are: bayes-an
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The categories of this paper are: funct-an
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The categories of this paper are: patt-sol