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Results

Next: About this document Up: Superresolution of SN 1987A: Previous: Modelling

Results

Image Features

We believe the central depression and the reality of the hotspots containing a significant portion, possibly 50%of the total flux.
The position angle of the hotspots agrees well with the FOC image, which is encouraging, but it not particularly well constrained by the radio image.
The suggestion of emission along the polar axis is not yet judged to be significant, as there is suspicious correlation between the MEM sky model and the residual image.
Our astrophysical interpretation of these images can be found in Staveley-Smith et al. (1993).

Algorithmic Results

MEM is the best algorithm found for superresolution in this study. GSP, Richardson-Lucy, and Maximum Emptiness are well behaved but suffer in robustness or resolution. CLEAN, NNLS, and SVD algebraic inversion are not recommended for superresolution.
When using MEM for superresolution, many more iterations are required than in normal suppression of sidelobes. Conventional wisdom holds that 40 iterations is usually sufficient. In this study, the image was still sharpening at 2000 iterations.
Effective resolution of MEM is a strong function of the close-in sidelobes of the PSF. Current work in progress has produced a PSF with sharper peak and better thermal noise than the conventional uniformly weighted PSF, at the expense of close-in sidelobes. The effective resolution in the MEM model gets worse, not better!

References

Staveley-Smith, L., Briggs, D. S., Rowe, A. C. H., Manchester, R. N., Reynolds, J. E., Tzioumis, A. K., Kestevan, M. J. 1993, Nature, 366, 136

Cornwell, T. J., &Evans, K. J. 1985, A&A, 143, 77

Narayan, R., &Nityananda, R. 1986, ARA&A, 24, 127

Högbom, J. A. 1974, A&AS, 15, 417

Jakobsen, P., et al., 1991, ApJ, 369, L63

Gonzalez, R., &Woods, R., 1992, Digital Image Processing, Addison-Wesley: Reading, Massachusetts

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