An interesting observed phenomenon of dayside auroral activity is the periodic sequence of moving bright forms observed at the polar cap boundary during southward-directed interplanetary magnetic field (IMF) conditions. The optical events reported here are elliptical-shaped bright 630.0 nm forms of ~200 km (N-S)¿300--500 km (E-W) spatial extent. They move eastward near the noon meridian with velocities of ~1.5 km s-1 and repeat at intervals of 5--10 min. Coordinated ground and satellite observations show that these auroral forms slow down and fade out after ~10 min., within the region of mantle precipitation. The present ground observations support the earlier indication that the direction of east-west motion along the polar cap boundary at/near magnetic noon is determined by the IMF BY polarity, consistent with models of field tension on magnetic flux tubes connected with the solar wind. The optical characteristics of the events documented here may have important implications for the nature of magnetic merging at the magnetopause and the associated transfer of energy and momentum to the ionosphere in the cusp/mantle region. ¿ American Geophysical Union 1992