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A long gamma-ray burst (LGRB) is a gamma-ray burst lasting more than two seconds. Those lasting less than two seconds are termed short gamma-ray burst (SGRBs). The events causing GRBs have been of research-interest since they were first detected. Current theory is that long-duration GRBs are caused by some particular core collapse supernovae (GRB supernovae), i.e., those of some rapidly-rotating, massive stars (e.g., Wolf-Rayet stars), this theory termed the collapsar model. They are Type Ic BL supernovae, the BL for broad lines from the rotation, and Type Ic BL SNe without GRBs are thought to be those that aimed the GRB in a direction other than toward Earth. The extremely bright gamma-ray emission is presumed to be aimed along the axis of rotation, or near it if generated by a magnetic field maintained and shaped by the rotation. Some spread of the directional burst is presumed to account for the numbers of LGRBs we observe.