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BLOBCAT: software to catalogue flood-filled blobs in radio images of total intensity and linear polarization

Lookup NU author(s): Dr Christopher Hales



This is the final published version of an article that has been published in its final definitive form by Oxford University Press, 2012.

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We present blobcat, new source extraction software that utilizes the flood fill algorithm to detect and catalogue blobs, or islands of pixels representing sources, in 2D astronomical images. The software is designed to process radio-wavelength images of both Stokes I intensity and linear polarization, the latter formed through the quadrature sum of Stokes Q and U intensities or as a by-product of rotation measure synthesis. We discuss an objective, automated method by which estimates of position-dependent background root mean square noise may be obtained and incorporated into blobcat's analysis. We derive and implement within blobcat corrections for two systematic biases to enable the flood fill algorithm to accurately measure flux densities for Gaussian sources. We discuss the treatment of non-Gaussian sources in light of these corrections. We perform simulations to validate the flux density and positional measurement performance of blobcat, and we benchmark the results against those of a standard Gaussian fitting task. We demonstrate that blobcat exhibits accurate measurement performance in total intensity and, in particular, linear polarization. blobcat is particularly suited to the analysis of large survey data. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Publication metadata

Author(s): Hales CA, Murphy T, Curran JR, Middelberg E, Gaensler BM, Norris RP

Publication type: Article

Publication status: Published

Journal: Monthly Notices of the Royal Astronomical Society

Year: 2012

Volume: 425

Issue: 2

Pages: 979-996

Print publication date: 11/09/2012

Date deposited: 30/06/2017

ISSN (print): 0035-8711

ISSN (electronic): 1365-2966

Publisher: Oxford University Press


DOI: 10.1111/j.1365-2966.2012.21373.x


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