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We present a physical interpretation for the locations of the sources ofradio emission in IM Pegasi (IM Peg, HR 8703), the guide star for theNASA/Stanford relativity mission Gravity Probe B. This emission is seen in eachof our 35 epochs of 8.4-GHz VLBI observations taken from 1997 to 2005. We foundthat the mean position of the radio emission is at or near the projected centerof the primary to within about 27% of its radius, identifying this active staras the radio emitter. The positions of the radio brightness peaks are scatteredacross the disk of the primary and slightly beyond, preferentially along anaxis with position angle, p.a. = (-38 +- 8) deg, which is closely aligned withthe sky projections of the orbit normal (p.a. = -49.5 +- 8.6 deg) and theexpected spin axis of the primary. Comparison with simulations suggests thatbrightness peaks are 3.6 (+0.4,-0.7) times more likely to occur (per unitsurface area) near the pole regions of the primary (|latitude| >= 70 deg) thannear the equator (|latitude| <= 20 deg), and to also occur close to the surfacewith ~2/3 of them at altitudes not higher than 25% of the radius of theprimary.

VLBI for Gravity Probe B. VI. The Orbit of IM Pegasi and the Location of the Source of Radio Emission