NASA/ESA Hubble Space Telescope colour images of gravitational lenses

NASA/ESA Hubble Space Telescope (HST) colour views of the distant quasar 1208+101 indicate that its image has been split in two by a gravitational lensing. The quasar was first observed with HST's Wide Field/Planetary Camera in July 1991 as part of the Snapshot Survey for gravitational lenses. The Snapshot Survey consists of short (about four minute) exposures of several hundred very bright, very distant quasars with the Wide Field/Planetary Camera. Current theories of gravitational lensing suggest that several of these quasars should be seen as multiple images with separations smaller than can be seen in ground-based observations.

Gravitational lensing is a phenomenon by which the pull of a massive object, such as a galaxy, can bend light from another, more distant, object as the light passes near or through it, focusing the light in multiple identical images. The high spatial resolution capability of HST allows searches for multiple images at separations of only 0.2 arc seconds; this is about five times smaller than can be done with ground-based instrumentation.