Milliarcsecond change of IM Pegasi radio position in 1 hour coincident with sharp rise in flux density

Continuum VLBI observations at 3.6 cm of the RS CVn binary star IM Pegasi (HR 8703) for similar to 16 hr beginning on 1997 January 16 revealed an apparent motion of the star's radio position that coincided temporally with a large relative change in its flux density. Specifically, a rise in flux density from 18 to 46 mJy in 1.4 hr coincided with a detected position change over that interval of (Delta alpha, Delta delta) = (-0.68 +/- 0.15, 0.55 +/- 0.20) mas. The magnitude of this position change is much larger than can be explained by parallax, proper motion, and orbital motion and is about two-thirds the estimated angular diameter of the primary component of the binary.