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Maser Source-Finding Methods in HOPS

Published online by Cambridge University Press:  02 January 2013

A. J. Walsh ,
C. Purcell ,
S. Longmore ,
C. H. Jordan  and
V. Lowe
A. J. Walsh*
Affiliation:
Centre for Astronomy, School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4814, Australia
C. Purcell
Affiliation:
School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
S. Longmore
Affiliation:
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
C. H. Jordan
Affiliation:
Centre for Astronomy, School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4814, Australia CSIRO Astronomy and Space Science, PO BOX 76, Epping, NSW 1710, Australia
V. Lowe
Affiliation:
CSIRO Astronomy and Space Science, PO BOX 76, Epping, NSW 1710, Australia School of Physics, University of NSW, Sydney, NSW 2052, Australia
*
FCorresponding author. Email: andrew.walsh@jcu.edu.au
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Abstract

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The H2O Southern Galactic Plane Survey (HOPS) has observed 100 deg2 of the Galactic plane, using the Mopra radio telescope to search for emission from multiple spectral lines in the 12-mm band (19.5–27.5 GHz). Perhaps the most important of these spectral lines is the 22.2-GHz water-maser transition. We describe the methods used to identify water-maser candidates and subsequent confirmation of the sources. Our methods involve a simple determination of likely candidates by searching peak emission maps, utilising the intrinsic nature of water-maser emission, spatially unresolved and spectrally narrow-lined. We estimate completeness limits and compare our method with results from the duchamp source finder. We find that the two methods perform similarly. We conclude that the similarity in performance is due to the intrinsic limitation of the noise characteristics of the data. The advantages of our method are that it is slightly more efficient in eliminating spurious detections and is simple to implement. The disadvantage is that it is a manual method of finding sources and so is not practical on datasets much larger than HOPS, or for datasets with extended emission that needs to be characterised. We outline a two-stage method for the most efficient means of finding masers, using duchamp.

Keywords

masersstars: formationsurveystechniques: spectroscopic
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 29 , Special Issue 3: Source Finding and Visualisation , 2012 , pp. 262 - 268
Copyright
Copyright © Astronomical Society of Australia 2012

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