Tobias Westmeier, Attila Popping, Paolo Serra
This paper presents and discusses the results of basic source finding tests
in three dimensions (using spectroscopic data cubes) with Duchamp, the standard
source finder for the Australian SKA Pathfinder. For this purpose, we generated
different sets of unresolved and extended HI model sources. These models were
then fed into Duchamp, using a range of different parameters and methods
provided by the software. The main aim of the tests was to study the
performance of Duchamp on sources with different parameters and morphologies
and assess the accuracy of Duchamp's source parametrisation. Overall, we find
Duchamp to be a powerful source finder capable of reliably detecting sources
down to low signal-to-noise ratios and accurately measuring their position and
velocity. In the presence of noise in the data, Duchamp's measurements of basic
source parameters, such as spectral line width and integrated flux, are
affected by systematic errors. These errors are a consequence of the effect of
noise on the specific algorithms used by Duchamp for measuring source
parameters in combination with the fact that the software only takes into
account pixels above a given flux threshold and hence misses part of the flux.
In scientific applications of Duchamp these systematic errors would have to be
corrected for. Alternatively, Duchamp could be used as a source finder only,
and source parametrisation could be done in a second step using more
sophisticated parametrisation algorithms.
View original:
http://arxiv.org/abs/1112.3093
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