Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: LOFAR imaging of the solar corona during the 2015 March 20 solar eclipse   The solar corona is a highly-structured plasma which can reach temperatures
of more than ~2 MK. At low frequencies (decimetric and metric wavelengths),
scattering and refraction of electromagnetic waves are thought to considerably
increase the imaged radio source sizes (up to a few arcminutes). However,
exactly how source size relates to scattering due to turbulence is still
subject to investigation. The theoretical predictions relating source
broadening to propagation effects have not been fully confirmed by observations
due to the rarity of high spatial resolution observations of the solar corona
at low frequencies. Here, the LOw Frequency ARray (LOFAR) was used to observe
the solar corona at 120-180 MHz using baselines of up to ~3.5 km (corresponding
to a resolution of ~1-2') during the partial solar eclipse of 2015 March 20. A
lunar de-occultation technique was used to achieve higher spatial resolution
(~0.6') than that attainable via standard interferometric imaging (~2.4'). This
provides a means of studying the contribution of scattering to apparent source
size broadening. It was found that the de-occultation technique reveals a more
structured quiet corona that is not resolved from standard imaging, implying
scattering may be overestimated in this region when using standard imaging
techniques. However, an active region source was measured to be ~4' using both
de-occultation and standard imaging. This may be explained by the increased
scattering of radio waves by turbulent density fluctuations in active regions,
which is more severe than in the quiet Sun.

27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
15
The categories of this paper are: nucl-ex
35
The categories of this paper are: mtrl-th
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
19
The categories of this paper are: eess
25
The categories of this paper are: patt-sol
5
The categories of this paper are: gr-qc
36
The categories of this paper are: cmp-lg
7
The categories of this paper are: hep-th
0
The categories of this paper are: hep-ph
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics