The Superluminal Character of the Compact Steep Spectrum Quasar 3C 216

We report the results of fourth epoch VLBI observations at 4990.99 MHz, with a resolution of ~1 mas, of the compact steep-spectrum quasar 3C216. Superluminal motion in this object is confirmed. Although a constant superluminal expansion at v_(app) = 3.9c ± 0.6 is not ruled out, our four epoch data are suggestive of component deceleration. In this paper we discuss the possibility of deceleration taking into account the compact steep spectrum nature of this quasar. We conclude that (a) compact steep spectrum sources may show the same beaming and orientation phenomena as extended sources and (b) the compact steep spectrum nature of the source could offer an explanation for the possible deceleration