| OSSE gamma-ray images (50-150 keV) in the direction of the constellation Virgo. The dark region contains the entire field with significant exposure time. Regions with insignificant exposure are shown as white surrounding area. The standard non-negative least squares (NNLS) reconstruction produces essentially a random noise field, while the Pixon reconstruction reveals two sources in this direction, 3C273 and NGC 4388, standing out prominently against a background with a mild brightness gradient. (The galaxy M87 also falls into the pixel containing NGC 4388, but it is not expected to contribute significantly to the gamma-ray emission.) Dave Dixon, UC Riverside, performed both the NNLS and the Pixon reconstructions. |
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