NULL RESULT IN GAMMA-RAY BURST LENSED ECHO SEARCH

We have searched for gravitational-lens-induced echoes between gamma-r ay bursts (GRBs) in BATSE data. The search was conducted in two phases , In the first phase we compared all GRBs in a brightness-complete sam ple of the first 260 GRBs with recorded angular positions having at le ast a 5% chance of being coincident from their combined positional err or. In the second phase, we compared all GRB light curves of the first 611 GRBs with recorded angular positions having at least a 55% chance of being coincident from their combined positional error. No unambigu ous gravitational lens candidate pairs were found in either phase, alt hough a ''library of close calls'' was accumulated for future referenc e. This result neither excludes nor significantly constrains a cosmolo gical origin for GRBs.