Archival search for recurrent activity at the position the gamma-ray   burst GRB 970228 optical counterpart
  We have examined 8004 plates at the Harvard College Observatory Plate Collection searching for optical transient emission from the gamma-ray burst GRB 970228. This is the first archival search carried out so far for a gamma-ray burst with known transient optical emission. The total exposure time amounts to ~1.1 yr. No convincing optical activity was found above 12.5 mag at the expected position of the GRB 970228 optical counterpart. 
Javier Gorosabel and Alberto J. Castro-Tirado