  Recent observations suggest that blobs of matter are ejected with
ultra-relativistic speeds in various astrophysical phenomena such as supernova
explosions, quasars, and microquasars. In this paper we analyze the
gravitational radiation emitted when such an ultra-relativistic blob is ejected
from a massive object. We express the gravitational wave by the metric
perturbation in the transverse-traceless gauge, and calculate its amplitude and
angular dependence. We find that in the ultra-relativistic limit the
gravitational wave has a wide angular distribution, like $1+\cos\theta$. The
typical burst's frequency is Doppler shifted, with the blue-shift factor being
strongly beamed in the forward direction. As a consequence, the energy flux
carried by the gravitational radiation is beamed. In the second part of the
paper we estimate the anticipated detection rate of such bursts by a
gravitational-wave detector, for blobs ejected in supernova explosions. Dar and
De Rujula recently proposed that ultra-relativistic blobs ejected from the
central core in supernova explosions constitute the source of Gamma-ray bursts.
Substituting the most likely values of the parameters as suggested by their
model, we obtain an estimated detection rate of about 1 per year by the
advanced LIGO-II detector.
