Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The 1997 hard state outburst of the X-ray transient GS 1354-64 / BW Cir   We present observations of the 1997 outburst of the X-ray transient GS
1354-64 (BW Cir) at X-ray, optical and, for the first time, radio wavelengths;
this includes upper limits to the linear and circular polarisation of the radio
data. The X-ray outburst was unusual in that the source remained in the
low/hard X-ray state throughout; the X-ray peak was also preceded by at least
one optical outburst, suggesting that it was an `outside-in' outburst - similar
to those observed in dwarf novae systems, although possibly taking place on a
viscous timescale in this case. It therefore indicates that the optical
emission was not dominated by the reprocessing of X-rays but that instead we
see the instability directly. While the radio source was too faint to detect
any extended structure, spectral analysis of the radio data and a comparison
with other similar systems suggests that mass ejections, probably in the form
of a jet, took place and that the emitted synchrotron spectrum may have
extended as far as infrared wavelengths. Finally, we compare this 1997 outburst
of GS 1354-64 with possible previous outbursts and also with other hard state
objects, both transient and persistent. It appears that a set of
characteristics -- such as a weak, flat spectrum radio jet, a mHz QPO
increasing in frequency, a surprisingly high optical:X-ray luminosity ratio and
the observed optical peak preceding the X-ray peak -- may be common to all hard
state X-ray transients.

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The categories of this paper are: hep-lat
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The categories of this paper are: eess
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The categories of this paper are: chao-dyn
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The categories of this paper are: supr-con
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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: math
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The categories of this paper are: solv-int
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The categories of this paper are: patt-sol
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The categories of this paper are: quant-ph
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The categories of this paper are: mtrl-th
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The categories of this paper are: bayes-an
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The categories of this paper are: chem-ph
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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: hep-ph