The electronic absorption spectra of the A(3) Pi(1) <-- X(1) Sigma(+) system of iodine bromides of Br-79 and Br-81 species were investigated in the region from 11 780 to 12 500 cm(-1) using a GaAs semiconductor laser and a titanium sapphire laser. The spectroscopic constants nu(0), B'(upsilon f), q'(upsilon), D'(upsilon), and B''(upsilon) for the upsilon = 8' <-- 3'', 9' <-- 3'', 11' <-- 4'', and 12' <-- 4'' bands were determined. The Q-branch lines of the upsilon = 7' <-- 3'', 4' <-- 4'', 5' <-- 4'', 10' <-- 4'', 6' <-- 5'', 7' <-- 5'', 13' <-- 5'', and 9' <-- 6'' bands were assigned and nu(0) - B'(upsilon f), B'(upsilon f), - B''(upsilon), and D'(upsilon) - D''(upsilon) were determined, (C) 1995 Academic Press, Inc.