CLASS B0445+123: a new two-image gravitational lens system

A new two-image gravitational lens system has been discovered as a result of the Cosmic Lens All-Sky Survey. Radio observations with the Very Large Array (VLA), the MultiElement Radio Linked Interferometer Network and the Very Long Baseline Array at increasingly higher resolutions all show two components with a flux density ratio of similar to7 : 1 and a separation of 1.34 arcsec. Both components are compact and have the same spectral index. Follow-up observations made with the VLA at 8.4 GHz show evidence of a feature to the south-east of the brighter component and a corresponding extension of the weaker component to the north-west. Optical observations with the William Herschel Telescope show similar to1.7-arcsec extended emission aligned in approximately the same direction as the separation between the radio components with an R -band magnitude of 21.8 +/- 0.4.