tokens: We wish to thank our colleagues from the Observatoire de Paris-Meudon and the NRH staff for providing the original visibility data. The authors are grateful to the other members of the ARTEMIS group, C. Caroubalos, P. Preka-Papadema, X. Moussas, A. Kontogeorgos and P. Tsitsipis, for their support work. We also wish to thank A. Nindos and S. Patsourakos for useful discussions and comments. Data from TRACE, GOES, the RSTN network, MTI/HXRS and HXT were obtained from the respective data bases; we are grateful to all those who contributed to the operation of these instruments and made the data available to the community.
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