A Joint Deconvolution Algorithm to Combine Single-dish and Interferometer Data for Wideband Multiterm and Mosaic Imaging

Abstract

Imaging in radio astronomy is usually carried out with a single-dish radio telescope doing a raster scan of a region of the sky or with an interferometer that samples the visibility function of the sky brightness. Mosaic observations are the current standard for imaging large fields of view with an interferometer, and multifrequency observations are now routinely carried out with both types of telescopes to increase the continuum imaging sensitivity and probe spectral structure. This paper describes an algorithm to combine wideband data from these two types of telescopes in a joint iterative reconstruction scheme that can be applied to spectral cube or wideband multiterm imaging both for narrow fields of view and for mosaics. Our results demonstrate the ability to prevent instabilities and errors that typically arise when wideband or joint mosaicking algorithms are presented with spatial and spectral structure that is inadequately sampled by the interferometer alone. For comparable noise levels in the single-dish and interferometer data, the numerical behavior of this algorithm is expected to be similar to the idea of generating artificial visibilities from single-dish data. However, our discussed implementation is simpler and more flexible in terms of applying relative data weighting schemes to match noise levels while preserving flux accuracy, fits within standard iterative image reconstruction frameworks, is fully compatible with wide-field and joint mosaicking gridding algorithms that apply corrections specific to the interferometer data, and may be configured to enable spectral cube and wideband multiterm deconvolution for single-dish data alone.