LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY
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 b...
| Main Authors: | , , , , , , , , , , , , , |
|---|---|
| Other Authors: | |
| Format: | Article |
| Language: | en_US |
| Published: |
IOP Publishing
2014
|
| Online Access: | http://hdl.handle.net/1721.1/88451 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 |
| _version_ | 1811096147811368960 |
|---|---|
| author | Cappallo, Roger J. Corey, Brian E. Goeke, Robert F. Hewitt, Jacqueline N. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Remillard, Ronald Alan Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Williams, Christopher Leigh |
| author2 | Haystack Observatory |
| author_facet | Haystack Observatory Cappallo, Roger J. Corey, Brian E. Goeke, Robert F. Hewitt, Jacqueline N. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Remillard, Ronald Alan Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Williams, Christopher Leigh |
| author_sort | Cappallo, Roger J. |
| collection | MIT |
| description | 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. |
| first_indexed | 2024-09-23T16:38:55Z |
| format | Article |
| id | mit-1721.1/88451 |
| institution | Massachusetts Institute of Technology |
| language | en_US |
| last_indexed | 2024-09-23T16:38:55Z |
| publishDate | 2014 |
| publisher | IOP Publishing |
| record_format | dspace |
| spelling | mit-1721.1/884512022-09-29T20:32:50Z LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY Cappallo, Roger J. Corey, Brian E. Goeke, Robert F. Hewitt, Jacqueline N. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Remillard, Ronald Alan Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Williams, Christopher Leigh Haystack Observatory MIT Kavli Institute for Astrophysics and Space Research Cappallo, Roger J. Corey, Brian E. Goeke, Robert F. Hewitt, Jacqueline N. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Remillard, Ronald Alan Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Williams, Christopher Leigh 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. National Science Foundation (U.S.) (Grant AST-0457585) National Science Foundation (U.S.) (Grant AST-0908884) National Science Foundation (U.S.) (Grant PHY-0835713) United States. Air Force Office of Scientific Research (Grant FA9550-0510247) Smithsonian Astrophysical Observatory MIT School of Science 2014-07-22T12:25:58Z 2014-07-22T12:25:58Z 2012-12 2012-07 Article http://purl.org/eprint/type/JournalArticle 0004-6256 1538-3881 http://hdl.handle.net/1721.1/88451 McKinley, B., F. Briggs, D. L. Kaplan, L. J. Greenhill, G. Bernardi, J. D. Bowman, A. de Oliveira-Costa, et al. “LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY.” The Astronomical Journal 145, no. 1 (January 1, 2013): 23. https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 en_US http://dx.doi.org/10.1088/0004-6256/145/1/23 The Astronomical Journal Creative Commons Attribution-Noncommercial-Share Alike http://creativecommons.org/licenses/by-nc-sa/4.0/ application/pdf IOP Publishing arXiv |
| spellingShingle | Cappallo, Roger J. Corey, Brian E. Goeke, Robert F. Hewitt, Jacqueline N. Kincaid, Barton B. Kratzenberg, Eric W. Lonsdale, Colin John McWhirter, Stephen R. Morgan, Edward H. Remillard, Ronald Alan Rogers, Alan E. E. Salah, J. E. Whitney, Alan R. Williams, Christopher Leigh LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title | LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title_full | LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title_fullStr | LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title_full_unstemmed | LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title_short | LOW-FREQUENCY OBSERVATIONS OF THE MOON WITH THE MURCHISON WIDEFIELD ARRAY |
| title_sort | low frequency observations of the moon with the murchison widefield array |
| url | http://hdl.handle.net/1721.1/88451 https://orcid.org/0000-0002-4117-570X https://orcid.org/0000-0001-7130-208X https://orcid.org/0000-0003-1941-7458 |
| work_keys_str_mv | AT cappallorogerj lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT coreybriane lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT goekerobertf lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT hewittjacquelinen lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT kincaidbartonb lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT kratzenbergericw lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT lonsdalecolinjohn lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT mcwhirterstephenr lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT morganedwardh lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT remillardronaldalan lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT rogersalanee lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT salahje lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT whitneyalanr lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray AT williamschristopherleigh lowfrequencyobservationsofthemoonwiththemurchisonwidefieldarray |