1998A&A...333..445G

New polarization-sensitive global VLBI and VLBA images of the BL Lacertae object BL 0716+714 at 6cm (1991.43) and 3.6cm/1.3cm (1994.22) are presented. The source shows a compact, one-sided core-jet structure in structural position angle ∼13°. Comparison with previously published data suggests that the apparent velocity of a 6 cm jet component is >0.82±0.11c, if the redshift of BL 0716+714 is z>0.3 (H₀=100km/s/Mpc; q₀=0.5). Linear polarization from the VLBI core was detected at all three frequencies. In addition, polarization from the innermost jet component was detected at 1.3cm. This compact jet polarization is quite high, ∼50%, and is aligned with the jet direction, suggesting it is a transverse shock. The VLBI core polarization at our earlier epoch was perpendicular to the VLBI jet direction, but aligned with the jet direction at the later epoch, about three years later. The available evidence suggests that the very rapid variability that is sometimes observed in BL 0716+714 occurs on more compact scales than those imaged by our VLB array.