Hα line profile observations of a limb flare with high temporal resolution.

We observed in Hσa the impulsive phase of a 1N/M2.0 limb flare on September 8, 1988 with high temporal resolution. With an imaging spectrograph line profiles have been acquired every 2.3 s. The temporal evolution in the blue and red wing has been correlated with hard X-ray data from HXRBS. It is shown that a prominent spike in the blue wing of Hα was delayed with respect to the corresponding hard X-ray burst by 7-8 s. With the exception of the spike in the blue wing of Hα, the temporal development of the line profile is compatible with the predictions for nonthermal electron heating during the impulsive phase. [ABSTRACT FROM AUTHOR]