Location of narrowband spikes in solar flares

Narrowband spikes of the decimeter type have been identified in dynamic spectrograms of Phoenix-2 of ETH Zurich and located in position with the Nancay Radioheliograph at the same frequency. The spike positions have been compared with the location of hard X-ray emission and the thermal are plasma in soft X-rays and EUV lines. The decimetric spikes are found to be single sources located some 20" to 400" away from the are site in hard or soft X-rays. In most cases there is no bright footpoint nearby. In at least two cases the spikes are near loop tops. These observations do not confirm the widely held view that the spike emission is produced by some loss-cone instability masering near the footpoints of are loops. On the other hand, the large distance to the are sites and the fact that these spikes are all observed in the are decay phase make the analyzed spike sources questionable sites for the main are electron acceleration. They possibly indicate coronal post-flare acceleration sites.