Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Discovery and Identification of MAXI J1621-501 as a Type I X-ray Burster
  with a Super-Orbital Period   MAXI J1621-501 is the first Swift/XRT Deep Galactic Plane Survey transient
that was followed up with a multitude of space missions (NuSTAR, Swift,
Chandra, NICER, INTEGRAL, and MAXI) and ground-based observatories (Gemini,
IRSF, and ATCA). The source was discovered with MAXI on 2017 October 19 as a
new, unidentified transient. Further observations with NuSTAR revealed 2 Type I
X-ray bursts, identifying MAXI J1621-501 as a Low Mass X-ray Binary (LMXB) with
a neutron star primary. Overall, 24 Type I bursts were detected from the source
during a 15 month period. At energies below 10 keV, the source spectrum was
best fit with three components: an absorbed blackbody with kT = 2.3 keV, a
cutoff power law with index $\Gamma{}$ = 0.7, and an emission line centered on
6.3 keV. Timing analysis of the X-ray persistent emission and burst data has
not revealed coherent pulsations from the source or an orbital period. We
identified, however, a super-orbital period $\sim{}$78 days in the source X-ray
light curve. This period agrees very well with the theoretically predicted
radiative precession period of $\sim{}$82 days. Thus, MAXI J1621-501 joins a
small group of sources characterized with super-orbital periods.

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The categories of this paper are: q-bio
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The categories of this paper are: hep-ex
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The categories of this paper are: plasm-ph
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The categories of this paper are: funct-an
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The categories of this paper are: comp-gas
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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: hep-ph
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The categories of this paper are: supr-con
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: acc-phys
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The categories of this paper are: physics
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The categories of this paper are: solv-int
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The categories of this paper are: dg-ga
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The categories of this paper are: eess