This unlabeled image of the first-ever foreground quasar (blue) lensing a background galaxy (red) was taken with the Keck II telescope and its NIRC-2 instrument using laser guide star adaptive optics. Discovering more of these lenses will allow astronomers to determine the masses of quasars’ host galaxies.
© F. Courbin, G. Meylan, S. G. Djorgovski, et al., EPFL/ Caltech/WMKO

This unlabeled image of the first-ever foreground quasar (blue) lensing a background galaxy (red) was taken with the Keck II telescope and its NIRC-2 instrument using laser guide star adaptive optics. Discovering more of these lenses will allow astronomers to determine the masses of quasars’ host galaxies.

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