An Improved Initial Orbit Determination Method Based on Perturbed Unit Vector Method

We considered 18 solar flares observed between June 2010 and July 2012, in which high energy >100 MeV gamma-emission was registered by the Large Area Telescope (LAT) aboard FermiGRO. We exainined for these y-events soft X-ray observations by GOES, hard X-ray observations by the Anti-Coincidence Shield of the SPectrometer aboard INTEGRAL (ACS SPI) and the Gamma-Ray burst Monitor (GBM) aboard FemiGRO. Hard X-ray and mu-decay gamma-ray emissions are used as tracers of electron and proton acceleration, respectively. Bursts of hard X-ray were observed by ACS SPI during impulsive phase of 13 events. Bursts of hard X-ray >100 keV were not found during time intervals, when prolonged hard y-emission was registered by LAT/FermiGRO. Those events showing prolonged high-energy gamma-ray emission not accompanied by >100 keV hard X-ray emission arc interpreted as an indication of either different acceleration processes for protons and electrons or as the presence of a proton population accelerated during the impulsive phase of the flare and subsequently trapped by some magnetic structure. In-situ energetic particle measurements by GOES and STEREO (High Energy Telescope, HET) shows that five of these y-events were not accompanied by SEP events at 1 AU, even when multi-point measurements including STEREO are taken into account. Therefore accelerated protons are not always released into the heliosphere. A longer delay between the inaximum temperature and the maxiinum einission measure characterises flares with prolonged high energy gamma-emission and solar proton events.