Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the Stability of the 421-day Periodicity in A0538-66   In this paper we analyse 70 years of archival Harvard and Schmidt plate data
of the 16.6 d Be X-ray binary A0538-66 in order to search for the presence of
the long-term period of 420.82 +/- 0.79 d found in MACHO photometry (Alcock et
al. 2001). We find evidence for a long-term period of 421.29 +/- 0.95 d in the
archival data, and examine its stability. We also combine the archival and
MACHO datasets in order to improve the accuracy of the orbital period
determination, using a cycle-counting analysis to refine its value to 16.6460
+/- 0.0004 d. We also test the model proposed in our previous paper (Alcock et
al. 2001) with observations documented in the literature for A0538-66 from
1980-1995, constraining the system inclination to be i > 74.9 +/- 6.5 deg.

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The categories of this paper are: dg-ga
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The categories of this paper are: gr-qc
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The categories of this paper are: plasm-ph
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The categories of this paper are: comp-gas
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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: q-alg
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The categories of this paper are: eess
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The categories of this paper are: solv-int
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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: hep-lat
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The categories of this paper are: patt-sol
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The categories of this paper are: cmp-lg
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The categories of this paper are: quant-ph
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The categories of this paper are: physics