Abstract:
Photographic observations with a 0.7 Å passband H-alpha Hale filter and morphological description of the double ribbon flare which occurred near Halle plage region 17926 on 1981 October 19 are described. Initially the flare appeared in the shape of the digit 3, but after some time it broke into two parallel strands. The flare was associated with several eruptive centres. From the observed data, we have estimated the separation and the velocity of separation of the two strands. We have also estimated the magnetic field associated with the flare and found it to be 75 and 238 gauss for ne = 10¹³ cm¯³ and 10¹⁴ cm¯³ respectively.
