SIMBAD references

We present four epoch images with milliarcsecond resolution, from VLBI (Very Long Baseline Interferometry) observations of the quasar DA 193 (J0555+3948) at 5GHz. The model-fitting results show that the source is resolved with a core-jet structure. A proper motion of 0.105±0.02mas/yr of the jet component was estimated, which corresponds to an apparent velocity of 4.5±0.86h^–1c at its redshift of z=2.365. Estimates of the Doppler factor and of the brightness temperature confirm that this source is considerably boosted towards the line of sight. The velocity is about 4 times larger than previous estimates, which may indicate (1) that the jet component is being accelerated, possibly due to a bending jet aligned close to the line of sight; or (2) that there are two different components ejected in two flares. The possibility that multiple ejection of short-lived components is taking place in the core region of DA 193 is also presented. Throughout this paper, the values q₀=0.5, H₀=100km/s/Mpc will be used.