Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Resolving the blazar CGRaBS J0809+5341 in the presence of telescope
  systematics   We analyse Very Long Baseline Interferometry (VLBI) observations of the
blazar CGRaBS J0809+5341 using Bayesian inference methods. The observation was
carried out at 5 GHz using 8 telescopes that form part of the European VLBI
Network. Imaging and deconvolution using traditional methods imply that the
blazar is unresolved. To search for source structure beyond the diffraction
limit, we perform Bayesian model selection between three source models (point,
elliptical Gaussian, and circular Gaussian). Our modelling jointly accounts for
antenna-dependent gains and system equivalent flux densities. We obtain
posterior distributions for the various source and instrumental parameters
along with the corresponding uncertainties and correlations between them. We
find that there is very strong evidence (>1e9 :1) in favour of elliptical
Gaussian structure and using this model derive the apparent brightness
temperature distribution of the blazar, accounting for uncertainties in the
shape estimates. To test the integrity of our method, we also perform model
selection on synthetic observations and use this to develop a Bayesian
criterion for the minimum resolvable source size and consequently the maximum
measurable brightness temperature for a given interferometer, dependent on the
signal-to-noise ratio (SNR) of the data incorporating the aforementioned
systematics. We find that calibration errors play an increasingly important
role in determining the over-resolution limit for SNR>>100. We show that it is
possible to exploit the resolving power of future VLBI arrays down to about 5
per cent of the size of the naturally-weighted restoring beam, if the gain
calibration is precise to 1 per cent or less.

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The categories of this paper are: q-fin
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The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
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The categories of this paper are: gr-qc
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-th
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The categories of this paper are: eess
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The categories of this paper are: math-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: hep-lat
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The categories of this paper are: alg-geom
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The categories of this paper are: chao-dyn
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The categories of this paper are: atom-ph
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The categories of this paper are: adap-org
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The categories of this paper are: q-bio