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R.A. Gaume, A.L. Fey, F.J. Vrba, N. Zacharias, A.A. Henden, H.H. Guetter (U.S. Naval Observatory)
Using the Very Long Baseline Array (VLBA) at a frequency of 2.265 GHz we have resolved the compact extragalactic radio source PKS~1445-161 into four individual components distributed in a region with a diameter < 200 milliarcseconds. The detailed spatial distribution of the four components is unusual for a source of this class. A simple gravitational lens model is presented wherein a background compact radio double is lensed by a foreground singular elliptical isothermal gravitational potential. The background double is lensed into several components whose predicted positions and flux densities are a good match to those of the observed radio components. The center of the model lens is coincident with the most intense of the 2.265 GHz radio components. This suggests that the strongest radio component marks the active nucleus of the foreground lensing galaxy. A 19th magnitude quasar is associated with PKS~1445-161. A comparison of the astrometric radio and optical positions of PKS~1445-161 shows that the optical quasar is spatially coincident with the most intense 2.265 GHz radio component. Arcsecond resolution near-infrared (2.2 \mum) images obtained with the 4-m telescope of the Kitt Peak National Observatory (KPNO) show PKS~1445-161 to be point-like, with no associated extended emission.
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