  The magnetic octupole moment of 87Rb is determined from hyperfine intervals
in the 5p 2P[3/2] state measured by Ye et al. [Opt. Lett. 21, 1280 (1996)].
Hyperfine constants A = 84.7189(22) MHz, B = 12.4942(43) MHz, and C = -0.12(09)
kHz are obtained from the published measurements. The existence of a
significant value for C indicates the presence of a nuclear magnetic octupole
moment Omega. Combining the hyperfine constants with atomic structure
calculations, we obtain Omega = -0.58(39) (b muN). Second-order corrections
arising from interaction with the nearby 5p 2P[1/2] state are found to be
insignificant.
