New optical and radio observations of the quadruple quasar H1413 + 117, the Cloverleaf, carried out with the 1.54 m Danish telescope at ESO and with the VLA at NRAO are presented. The VLA data, obtained in the A configuration at 3.6 cm, show radio counterparts at the positions of the four optical images and an additional strong radio source between images B and D. Gravitational lens models of H1413 + 117 using (a) a single elliptical galaxy and (b) two spherical galaxies are presented, which fit the positions of the four images of the quasar remarkably well. The models suggest that the strong radio source is a feature of the quasar, e.g., an ejected blob, which lies right on the caustic of the lens and is thereby strongly amplified. The time delays predicted by our models are sufficiently short to allow for their determination within one observational season, making H1413 + 117 an exceptionally well suited object for gravitational lens research.
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Kayser et al. (1990) studied this question.