Astronomers measured the distance to a faint galaxy from which the burst originated. While gamma-ray bursts last only a few seconds, their afterglows can be studied for several months. By analyzing these afterglows, astronomers have discovered that the bursts do not originate within our own galaxy, the Milky Way, but rather are associated with extremely distant galaxies. The Hubble telescope images of GRB971214 confirmed the association of the burst's afterglow with a faint galaxy. Astronomers still don't understand the origins of bursts.
Theories suggest they happen where vigorous star formation takes place.
Gamma-ray bursts may be created by the mergers of a pair of neutron stars or black holes or a hypernova, a theorized type of exceptionally violent exploding star.