Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: GRB 020531: A Short, Hard Gamma-Ray Burst Localized and Observed by
  HETE-2   The HETE-2 FREGATE and WXM instruments detected a short, hard GRB at
00:26:18.72 UT on 31 May 2002. A preliminary localization was reported as a GCN
Position Notice 88 min after the burst, and a refined localization was
disseminated 123 minutes later. An IPN localization of the burst was reported
18 hours after the GRB, and a refined IPN localization was disseminated ~5 days
after the burst. The final IPN localization, disseminated on 25 July 2002, is a
diamond-shaped region centered on RA=15h 15m 11.18s, Dec=-19o 24' 27.08"
(J2000), and has an area of ~9 square arcminutes (99.7% confidence region). The
prompt localization of the burst by HETE-2, coupled with the refinement of the
localization by the IPN, made possible the most sensitive follow-up
observations to date of a short, hard GRB at radio, optical, and X-ray
wavelengths. The time history of GRB020531 at high (>30 keV) energies consists
of a short, intense spike followed by a much less intense secondary peak, which
is characteristic of many short, hard bursts. The duration of the burst
increases with decreasing energy and the spectrum of the burst evolves from
hard to soft, behaviors which are similar to those of long GRBs. This suggests
that short, hard GRBs are closely related to long GRBs.

37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
8
The categories of this paper are: hep-ex
31
The categories of this paper are: ao-sci
20
The categories of this paper are: acc-phys
3
The categories of this paper are: physics
4
The categories of this paper are: cond-mat
22
The categories of this paper are: chao-dyn
5
The categories of this paper are: gr-qc
26
The categories of this paper are: bayes-an
28
The categories of this paper are: alg-geom