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Use of a Surface Polarizer to Reduce the Spectral Baseline Ripple of the Parkes Telescope

Published online by Cambridge University Press:  25 April 2016

D. R. Williams  and
B. MacA. Thomas
D. R. Williams
Affiliation:
Division of Radiophysics, CSIRO, Sydney
B. MacA. Thomas
Affiliation:
Division of Radiophysics, CSIRO, Sydney
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Extract

Baseline ripple measurements are of two general kinds, those associated with on-source mechanisms and those with off-source mechanisms (Poulton 1974; Morris 1974). We are here principally concerned with on-source baseline ripples, which occur when a strong continuum radio source is present in the beam. The ripples are particularly conspicuous (Padman 1977, 1978) with a large instrument, such as the Parkes 64-m telescope, where the ripple period is rapid. Here baseline uncertainty becomes especially severe for the detection and study of wide lines, such as the H/He complex and the formamide multiplet near 1.54 GHz. Off-source baseline ripples also occur because of other effects, but in principle they can be removed by subtracting a reference-region spectrum taken while tracking the telescope over the same hour-angle range at the same declination under stable conditions. Improvement of the off-source baseline ripple which arises from stray radiation would also be expected to result from the technique described here.

Type
Contributions
Information
Publications of the Astronomical Society of Australia , Volume 4 , Issue 1 , 1980 , pp. 33 - 37
Copyright
Copyright © Astronomical Society of Australia 1980

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References

Jull, E.V., Electron. Lett., 15, 423 (1979).Google Scholar
Minnett, H. C., and Thomas, B. Mac, A., Proc. IEE, 115, 1419 (1968).Google Scholar
Morris, D., Meudon Observatory Rapport Interne G.I. mm. No. 125a (April) (1974).Google Scholar
Padman, R., Proc. Astron. Soc. Aust., 3, 111 (1977).Google Scholar
Padman, R., Division of Radiophysics, Int. Rep. RPP 2056(L) (1978).Google Scholar
Poulton, G.P., CSIRO Division of Radiophysics Int. Rep. RPP 2170(L) (1974).Google Scholar
Williams, D.R., Weinreb, S., and Lum, W., Microwave J., 23, (1980).Google Scholar