Interplanetary network localization of GRB 991208 and the discovery of itsafterglow

The extremely energetic (similar to 10(-4) ergs cm(-2)) gamma-ray burst (GR B) of 1999 December 8 was triangulated to an similar to 14 arcmin(2) error box similar to 1.8 days after its arrival at Earth with the third interplan etary network (IPN), which consists of the Ulysses, Near-Earth Asteroid Ren dezvous, and Wind spacecraft. Radio observations with the Very Large Array similar to 2.7 days after the burst revealed a bright fading counterpart wh ose position is consistent with that of an optical transient source with a redshift of 0.707. We present the time history, peak flux, fluence, and ref ined 1.3 arcmin(2) error box of this event and discuss its energetics. This is the first time that a counterpart has been found for a GRB localized on ly by the IPN.