We present the results of optical ( R band ) photometric and polarimetric monitoring and Very Long Baseline Array ( VLBA ) imaging of the blazar ( catalog S4~0954+658 ) , along with Fermi \gamma -ray data during a multi-waveband outburst in 2011 March-April .
After a faint state with a brightness level R \sim 17.6 mag registered in the first half of January 2011 , the optical brightness of the source started to rise and reached \sim 14.8 mag during the middle of March , showing flare-like behavior .
The most spectacular case of intranight variability was observed during the night of 2011 March 9 , when the blazar brightened by \sim 0.7 mag within 7 hours .
During the rise of the flux the position angle of optical polarization rotated smoothly over more than 300° .
At the same time , within 1 \leavevmode \nobreak \sigma uncertainty a new superluminal knot appeared with an apparent speed of 19.0 \pm 0.3 \leavevmode \nobreak c .
We have very strong evidence for association of this knot with the multi-waveband outburst in 2011 March-April .
We also analyze the multi-frequency behavior of ( catalog S4~0954+658 ) during a number of minor outbursts from August 2008 to April 2012 .
We find some evidence of connections between at least two more superluminal ejecta and near-simultaneous optical flares .