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Proceedings Paper

A novel imaging algorithm for broadband aperture synthesis data
Author(s): Christian A. Hummel
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Paper Abstract

I developed a new imaging algorithm allowing the combination of multi-channel interferometric data in a single image. The method is applicable to sources emitting optically thick radiation where the dependence of the source structure on wavelength can therefore be described by a single parameter, i.e. the (local) effective temperature. The result of the imaging process is an intensity map as well as a map of the effective temperature across the source. The advantage of this method over the independent imaging of data in each channel is the benefit of a much better DB ("dirty beam", also PSF) when combining the aperture coverage of each channel over a wide range of wavelengths. I present results from applications to composite spectrum binaries and stellar surfaces of rotating stars based on simulated data. My imaging algorithm is based on the well known CLEAN method, adding the effective temperature as an additional parameter for each image pixel. This information can be used to scale the PSF in each channel with the blackbody law and subtract it from the combined residual map. Once a cleaned map has been obtained (using regular phase self-calibration techniques) and thus a set of phase-corrected visibilities, individual channel maps are obtained by running the CLEAN restricted to non-zero pixels. The cleaned channel maps together with the total flux spectrum can then be used to estimate the blackbody temperature for each non-zero image pixel, and used for the next iteration of the modified CLEAN algorithm.

Paper Details

Date Published: 21 July 2010
PDF: 6 pages
Proc. SPIE 7734, Optical and Infrared Interferometry II, 77342H (21 July 2010); doi: 10.1117/12.856363
Show Author Affiliations
Christian A. Hummel, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 7734:
Optical and Infrared Interferometry II
William C. Danchi; Françoise Delplancke; Jayadev K. Rajagopal, Editor(s)

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