An early VLBI observation of the quasar 3C 286

Using the hybrid mapping technique based on self-calibration and CLEAN algo rithms, we reprocessed the data of an early (1976) VLBI observation (by T. J. Pearson et al.) of quasar 3C 286 at 18 cm, and obtained a high quality C LEAN map. We can get more information from the new map than from the old on e. Four Gaussian models were used to fit the calibrated UV data. We found t hat the central bright region could be resolved into two compact components . This was in accordance with the later higher angular resolution VLBI obse rvations. Comparing with the results of other VLBI observations, the distan ce between these two components was found to vary not only with frequency a t a given time, but also with time at a fixed frequency.