Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deviations from the Flux-Recurrence Time Relationship in GS 1826-238:
  Potential Transient Spectral Changes   The low-mass X-ray binary GS 1826-238 is presently unique for its
consistently regular bursting behavior. In previous Rossi X-Ray Timing Explorer
(RXTE) measurements between 1997 November and 2002 July, this source exhibited
(nearly) limit-cycle bursts with recurrence times that decreased
proportionately as the persistent flux increased. Here we report additional
measurements of the burst recurrence time by RXTE, Chandra, and XMM-Newton, as
well as observations of optical bursts. On a few occasions we measured burst
recurrence times which deviated significantly from the earlier flux-recurrence
time relationship, and most of these bursts occurred earlier than would be
predicted based on the X-ray flux level. The epochs with early bursts were also
accompanied by unusual broadband timing signatures, with the entire power
spectrum shifting to higher frequencies. Concurrent XMM-Newton observations
during one of these occasions, in 2003 April, indicate that an additional soft
component may be present in the spectrum containing enough flux (30% of the
total) to account for the burst recurrence time discrepancy. A self-consistent
interpretation for the increase in soft flux and accompanying timing changes
during 2003 April is that accretion disk extends down to smaller radial
distances from the source than during the other observing epochs. The RXTE
observations since 2003 April show that the spectral and timing properties have
nearly returned to the previously established level.

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The categories of this paper are: q-alg
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The categories of this paper are: quant-ph
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The categories of this paper are: math-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: ao-sci
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-lat
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The categories of this paper are: cond-mat
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The categories of this paper are: chem-ph
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: cs
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The categories of this paper are: adap-org
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The categories of this paper are: dg-ga
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-ex