SAR arc occurrence frequency during cycle 23 of solar activity

The occurrence frequency of SAR arcs during 1997–2006 has been analyzed based on the photometric observations at the Yakutsk meridian (Maimaga station, corrected geomagnetic coordinates: 57° N, 200° E). SAR arcs appeared in 114 cases (∼500 h) during ∼370 nights of observations (∼3170 h). The occurrence frequency of SAR arcs increases to 27% during the growth phase of solar activity and has a clearly defined maximum ∼36% at a decline of cycle 23. The SAR arc registration frequency corresponds to the variations in geomagnetic activity in this solar cycle. The dates, UT, and geomagnetic latitudes of photometric observations are presented for 1997–2006.