Photographic and photometric observations of mid-latitude red arcs

Stable auroral red arcs (SAR-arcs) were observed in Majmaga (ΦS∼56.5deg) at the Yakutsk meridian in November-December, 1987 and February, 1988. The SAR-arcs were observed to the equator of diffuse glow, located at lower latitudes with respect to discrete auroral forms, obviously, in the external plasmospheric projection area. It is noted that they appear both in disturbed periods and in those with medium magnetic activity (Kp=3). The SAR-arc height is ∼450km