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The discovery of HDF J123652621227, a candidate gravitational lens in the Hubble Deep Field, is reported. This lens may be multiply imaging several optical sources at different redshifts. If follow-up spectroscopy of the lens and the brightest image confirms this hypothesis, observations of this system alone can be used to obtain an estimate of the redshift distribution at extremely faint flux levels.
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Hogg et al. (1996) studied this question.
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