Will GRB 990123 perform an encore?

The recent gamma-ray burst GRB 990123 has an absorption redshift z(s) = 1.6 0, implying an apparent energy E greater than or equal to 3 x 10(54) erg, a nd a peak luminosity L-max greater than or equal to 6 x 10(53) erg s(-1), a ssuming isotropic emission. This energy is 10 times larger than hitherto me asured, and in excess of the rest mass of the Sun. Optical observations hav e revealed an associated galaxy displaced from the line of sight by similar to 0.6 arcsec. This raises the possibility that the burst is enhanced by g ravitational lensing. We argue that existing observations probably only all ow magnifications mu > 400 if the galaxy is at z(d) = 1.60 and the burst or iginates at much higher redshift. It should be possible to exclude this pos sibility by examining the burst time structure. Although we anticipate that multiple imaging can be excluded in GRB 990123, our analysis should be gen erally applicable.