... These Apache Point Observatory optical images from Monday and Tuesday this week have helped identify a faint, fading object (red arrow) near the position of a gamma-ray burst . The gamma-ray burst triggered satellite observatories on Sunday, December 14th. ... Though thousands of bursts have been detected by satellites sensitive to gamma rays, it is likely that this object represents only the third known optical counterpart to a gamma-ray burst . ... GRB 990510: Another Unusual Gamma Ray Burst . ...