Multi-frequency VLBI observations of OT 081

We have observed OT 081 at 4.8, 8.4, 15, and 22 GHz, with the VLBI Space Ob servatory Programme (VSOP) and the Very-Long-Baseline Array (VLBA) after it s radio burst on 1998 May. Multi-frequency VLBI images show a dominant comp onent D and a weak component C1, which is a knot of the jet extending to th e north-west direction. The derived physical parameters of component D are the Doppler factor, delta (eq) similar to 32.0, the Lorentz factor of 16.0 < <Gamma> < 16.9, and the viewing angle, <phi> < 0.<degrees>68. It appears that although delta (eq) of component C1 is smallar than that of componet D by one order of magnitude, Gamma of component C1 is about twice the range as that of component D at the 1 sigma level. However, phi of component D is different from that of component CI. The rapid variability of the flux den sity of OT 081 is suggested to be due to the variation of phi.