科研之友
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摘要
We have investigated a technique of combining single-dish data and interferorneter data in the spatial frequency domain, using imaging simulations and analytical considerations. Our study shows that there is an optimum of the relative weights between the visibility data of a single-dish and an interferorneter. The quality of the reconstructed combined image achieves the highest values at relative weights where the mean of the difference between the synthesized beam and the CLEAN beam is close to zero. We also examined the (u,v)-range that can be effectively used for the data combining by considering a blurring effect due to a pointing error. The error in single-dish deconvolution caused by the beam approximation is small with a large diameter of the single-dish aperture. The diameter should be at least 1.7-times larger than the minimum baseline of the interferometer for an amplitude accuracy better than 10%. Furthermore, we derived an estimate of the noise variance in the combined image, which agrees with our simulation results. The noise-added simulations demonstrate that there is a threshold of the noise level of the single-dish image, beyond which a large-scale error is emphasized in the combined image. We should take observation times to make at least the same noise level at the border of the spatial frequency between the single-dish and the interferometer. Although our examinations were assumed to use the 45 m telescope and NMA, our results concerning the required conditions for observations and data processes can be used in a general case of heterogeneous array imaging.
- 出版日期2009
- 单位中国科学院国家天文台
