Observations of Sympathetic Flares on Nobeyama Radio Heliograph

V.E. Abramov-Maximov$^1$, G.B. Gelfreikh$^1$, K. Shibasaki$^2$

$^1$ Pulkovo Astronomical Observatory, Russian Academy of Sciences, St.-Petersburg 196140, Russia
$^2$Nobeyama Radio Observatory, National Astronomical Observatory of Japan, Minamimaki, Minamisaku, Nagano 384-1305, Japan

The sympathetic effects were detected in 1930-s from analyzing optical flare statistics. For a long time the reality of the effect was in the stage of discussion. New results on the manifestation of the flare activity obtained from cosmos in X-rays and EUV gave firmer confirmation of reality of sympathetic effects. Nevertheless its physical nature and significance for study the nature of the solar activity is under investigation. So, all accessible ways to study the nature and manifestation of the sympathetic events are worth to consider.

In this study we present the case (June 30, 2003) when three sympathetic pares of flares happened in two ARs (NOAA 397 and NOAA 396) at large distance (more than 90 degrees on latitude) were registered with delay of time from ten to twenty minutes at wavelength 1.76 cm. That implies that the velocity of the agent causing the observed effect was not less than 1000 km/sec. Three flares during one day persuade that it is not by chance. In fact, it is the first case when sympathetic flares was found from NoRH data.

The analysis above have demonstrated that the NoRH is a very suitable instrument for investigations of sympathetic flares, due to long series of observations (since 1992 till now), high time (1 sec) and spatial (10$^\prime$$^\prime$) resolution for full solar disk, possibility to use long daily periods of observations (up to 8 hours per day).