Ground-based photometric observation of the postnoon dayside cleft region was carried out at Sachs Harbour (&Lgr;=76.7¿) during the period November 30--December 19, 1977 by using a 6-channel meridian-scanning photometer. Continuous observation of the 6300-¿ I emission permitted the mapping of the postnoon cleft morphology. The cleft was located at 77¿--78¿ &Lgr; on geomagnetically quiet days and farther equatorward by 2¿--3¿ on the most active days (Kp=4). During each afternoon an equatorward movement of the cleft was observed after about 140 MLT. The peak intensity of the 6300-¿ emission was usually 1--2 kR. A distinction is made between 'soft' cleft characteristics identified early on several afternoons, when the 6300-¿ emission rate is always greater than that at 5577-¿, and a more structured character seen at all other times. The structure takes the form of transient enhancements of the auroral emissions, particularly 5577 ¿. The enhancements have a duration of about 1 min and tend to occur as sequences. On none of the 10 clear days of observations was there optical evidence of energetic electron precipitation equatorward of the cleft.