LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY
- Research School of Astronomy and Astrophysics, Australian National University, Canberra (Australia)
- Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI (United States)
- Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ (United States)
- ARC Centre of Excellence for All-Sky Astrophysics (CAASTRO), School of Physics, The University of Sydney, Sydney, NSW (Australia)
- National Centre for Radio Astrophysics, Tata Institute for Fundamental Research, Pune (India)
- School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington (New Zealand)
- International Centre for Radio Astronomy Research, Curtin University, Perth (Australia)
- Center for Astrophysics and Supercomputing, Swinburne University of Technology, Melbourne (Australia)
- CSIRO Astronomy and Space Science, Canberra (Australia)
- MIT Haystack Observatory, Westford, MA (United States)
- Raman Research Institute, Bangalore (India)
- Sydney Institute for Astronomy, School of Physics, University of Sydney, Sydney (Australia)
- MIT Kavli Institute for Astrophysics and Space Research, Cambridge, MA (United States)
A new generation of low-frequency radio telescopes is seeking to observe the redshifted 21 cm signal from the epoch of reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of wide-field low-frequency radio interferometry. Precise calibration will be required to separate the expected small EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300 MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognized frequency modulated (FM) radio band. The observations have implications for future low-frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at meter wavelengths to an observer beyond our own solar system.
- OSTI ID:
- 22089725
- Journal Information:
- Astronomical Journal (New York, N.Y. Online), Vol. 145, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 1538-3881
- Country of Publication:
- United States
- Language:
- English
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