Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The gamma-ray giant flare from SGR1806-20: Evidence for crustal cracking
  via initial timescales   We report here on serendipitous observations of the intense gamma-ray flare
from SGR 1806-20 that occured on 27 December 2004. Unique data from the Cluster
and Double Star-2 satellites, designed to study the Earth's magnetosphere,
provide the first observational evidence of three separate timescales within
the early (first 100ms) phases of this class of events. These observations
reveal that, in addition to the initial very steep (<0.25ms) X-ray onset, there
is firstly a 4.9ms exponential rise timescale followed by a continued
exponential rise in intensity on a timescale of 70ms. These three timescales
are a prominent feature of current theoretical models including the timescale
(several ms) for fracture propagation in the crust of the neutron star.

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The categories of this paper are: nucl-th
4
The categories of this paper are: cond-mat
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
21
The categories of this paper are: adap-org
17
The categories of this paper are: q-fin
26
The categories of this paper are: bayes-an
34
The categories of this paper are: chem-ph
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int