Hydra ii: Characterisation of Aegean, Caesar, profound, pybdsf, and selavy source finders
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Date
2023Author
Boyce, M. M.
Hopkins, A. M.
Vaccari, Mattia
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We present a comparison between the performance of a selection of source finders using a new software
tool called Hydra. The companion paper, Paper I, introduced the Hydra tool and demonstrated its
performance using simulated data. Here we apply Hydra to assess the performance of different source
finders by analysing real observational data taken from the Evolutionary Map of the Universe (EMU)
Pilot Survey. EMU is a wide-field radio continuum survey whose primary goal is to make a deep
(20μJy/beam RMS noise), intermediate angular resolution (15′′), 1 GHz survey of the entire sky south
of +30◦ declination, and expecting to detect and catalogue up to 40 million sources. With the main
EMU survey expected to begin in 2022 it is highly desirable to understand the performance of radio
image source finder software and to identify an approach that optimises source detection capabilities.
Hydra has been developed to refine this process, as well as to deliver a range of metrics and source
finding data products from multiple source finders. We present the performance of the five source finders
tested here in terms of their completeness and reliability statistics, their flux density and source size
measurements, and an exploration of case studies to highlight finder-specific limitations.