Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: A Photometric Investigation of the GRB970228 Afterglow and the
  Associated Nebulosity   We carefully analyze the WFPC2 and STIS images of GRB970228. We measure
magnitudes for the GRB970228 point source component in the WFPC2 images of
$V=26.20^{+0.14}_{-0.13}$, $I_c=23.94^{+0.10}_{-0.09}$ and
$V=26.52^{+0.16}_{-0.18}$, $I_c=24.31^{+0.15}_{-0.11}$ on March 26 and April 7,
respectively; and $R_c=27.09^{+0.14}_{-0.14}$ on September 4 in the STIS image.
For the extended component, we measure magnitudes of
$R_c=25.48^{+0.22}_{-0.20}$ in the combined WFPC2 images and
$R_c=25.54^{+0.33}_{-0.22}$ in the STIS image, which are consistent with no
variation. This value is fainter than previously reported (Galama et al. 98)
and modifies the previously assumed magnitudes for the optical transient when
it faded to a level where the extended source component contribution was not
negligible, alleviating the discrepancy to a power-law temporal behavior. We
also measure a color of $V_{606}-I_{814}=-0.18^{+0.51}_{-0.61}$ for the
extended source component. Taking into account the extinction measured in this
field (Castander & Lamb 1998), this color implies that the extended source is
most likely a galaxy with ongoing star formation.

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The categories of this paper are: nlin
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The categories of this paper are: chao-dyn
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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: cs
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The categories of this paper are: alg-geom
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The categories of this paper are: physics
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: econ
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The categories of this paper are: bayes-an
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The categories of this paper are: math-ph
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The categories of this paper are: eess
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The categories of this paper are: cmp-lg
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The categories of this paper are: adap-org