Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Deep MERLIN 5GHz Radio Imaging of Supernova Remnants in the M82
  Starburst   The results of an extremely deep, 8-day long observation of the central kpc
of the nearby starburst galaxy M82 using MERLIN (Multi-Element Radio Linked
Interferometer Network) at 5 GHz are presented. The 17E-06 Jy/beam, rms noise
level in the naturally weighted image make it the most sensitive high
resolution radio image of M82 made to date. Over 50 discrete sources are
detected, the majority of which are supernova remnants, but with 13 identified
as HII regions. Sizes, flux densities and radio brightnesses are given for all
of the detected sources, which are all well resolved with a majority showing
shell or partial shell structures. Those sources within the sample which are
supernova remnants have diameters ranging from 0.3 to 6.7 pc, with a mean size
of 2.9 pc.
  From a comparison with previous MERLIN 5 GHz observations made in July 1992,
which gives a 9.75 year timeline, it has been possible to measure the expansion
velocities of ten of the more compact sources, eight of which have not been
measured before. These derived expansion velocities range between 2200 and
10500 km/s.

15
The categories of this paper are: nucl-ex
13
The categories of this paper are: quant-ph
4
The categories of this paper are: cond-mat
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
17
The categories of this paper are: q-fin
24
The categories of this paper are: dg-ga
32
The categories of this paper are: atom-ph
11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
22
The categories of this paper are: chao-dyn
3
The categories of this paper are: physics
18
The categories of this paper are: econ