Time smearing: Difference between revisions
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'''Time smearing''' or '''time-average smearing''' is the degradation of the reconstructed image of a [[celestial body]] [[astronomical observation|observed]] by a ground-based [[astronomical interferometer|interferometer]] that occurs because of the [[time|duration]] of the observation. Unlike single [[telescope]]s or [[camera]]s that can compensate the Earth's rotation in real time with a dedicated [[telescope mount|mount]], the different telescopes of the interferometer are at fixed positions on the Earth. As a result, maps obtained with interferometers feature the elongated orthoradial features similar to those of [[night sky]] photographs taken with a fixed [[tripod]], unless they use short enough integration times. |
'''Time smearing''' or '''time-average smearing''' is the degradation of the reconstructed image of a [[celestial body]] [[astronomical observation|observed]] by a ground-based [[astronomical interferometer|interferometer]] that occurs because of the [[time|duration]] of the observation. Unlike single [[telescope]]s or [[camera]]s that can compensate the Earth's rotation in real time with a dedicated [[telescope mount|mount]], the different telescopes of the interferometer are at fixed positions on the Earth. As a result, maps obtained with interferometers feature the elongated orthoradial features similar to those of [[night sky]] photographs taken with a fixed [[tripod]], unless they use short enough integration times. |
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Revision as of 12:52, 31 May 2020
 | This article may be too technical for most readers to understand. (June 2012) |
Time smearing or time-average smearing is the degradation of the reconstructed image of a celestial body observed by a ground-based interferometer that occurs because of the duration of the observation. Unlike single telescopes or cameras that can compensate the Earth's rotation in real time with a dedicated mount, the different telescopes of the interferometer are at fixed positions on the Earth. As a result, maps obtained with interferometers feature the elongated orthoradial features similar to those of night sky photographs taken with a fixed tripod, unless they use short enough integration times.
The smearing is a problem for long integration times or very separated telescopes. Mostly an issue in radioastronomy, it severely limits the usable field of view of observations in very long baseline interferometry.
References
- Bridle, Alan H. and Schwab, Frederic R., Wide Field Imaging I: Bandwidth and Time-Average Smearing in Synthesis imaging in radio astronomy (1989), eds. Richard A. Perley, Frederic R. Schwab, Astronomical Society of the Pacific Conference Series, vol. 6, ISBN 0-937707-23-6, p. 247.
