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Characterisation of the Mopra Radio Telescope at 16–50 GHz

Published online by Cambridge University Press:  02 January 2013

J. S. Urquhart ,
M. G. Hoare ,
C. R. Purcell ,
K. J. Brooks ,
M. A. Voronkov ,
B. T. Indermuehle ,
M. G. Burton ,
N. F. H. Tothill  and
P. G. Edwards
J. S. Urquhart*
Affiliation:
Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
M. G. Hoare
Affiliation:
School of Physics and Astronomy, University of Leeds, Leeds, LS2 9JT, UK
C. R. Purcell
Affiliation:
University of Manchester, Jodrell Bank Centre for Astrophysics, Manchester, M13 9LP, UK
K. J. Brooks
Affiliation:
Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
M. A. Voronkov
Affiliation:
Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
B. T. Indermuehle
Affiliation:
Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
M. G. Burton
Affiliation:
School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
N. F. H. Tothill
Affiliation:
School of Physics, University of New South Wales, Sydney, NSW 2052, Australia
P. G. Edwards
Affiliation:
Australia Telescope National Facility, CSIRO Astronomy and Space Science, Sydney, NSW 2052, Australia
*
EEmail: [email protected] (ATNF)
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Abstract

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We present the results of a programme of scanning and mapping observations of astronomical masers and Jupiter designed to characterise the performance of the Mopra Radio Telescope at frequencies between 16 and 50 GHz using the 12-mm and 7-mm receivers. We use these observations to determine the telescope beam size, beam shape, and overall telescope beam efficiency as a function of frequency. We find that the beam size is well fit by λ/D over the frequency range with a correlation coefficient of ∼90%. We determine the telescope main beam efficiencies are between ∼48 and 64% for the 12-mm receiver and reasonably flat at ∼50% for the 7-mm receiver. Beam maps of strong H2O (22 GHz) and SiO masers (43 GHz) provide a means to examine the radial beam pattern of the telescope. At both frequencies, the radial beam pattern reveals the presence of three components: a central ‘core’, which is well fit by a Gaussian and constitutes the telescopes main beam; and inner and outer error beams. At both frequencies, the inner and outer error beams extend out to ∼2 and ∼3.4 times the full-width half maximum of the main beam, respectively. Sources with angular sizes of a factor of two or more larger than the telescope main beam will couple to the main and error beams, and therefore the power contributed by the error beams needs to be considered. From measurements of the radial beam power pattern we estimate the amount of power contained in the inner and outer error beams is of order one-fifth at 22 GHz, rising slightly to one-third at 43 GHz.

Keywords

instrumentsISM: moleculesradio sources: lines
Type
Research Article
Information
Publications of the Astronomical Society of Australia , Volume 27 , Issue 3 , 2010 , pp. 321 - 330
Copyright
Copyright © Astronomical Society of Australia 2010

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