A database combining information about solar proton enhancements (SPEs) near the Earth and soft X-ray flares (GOES measurements) has been used for the study of different correlations through the period from 1975 to May 2006. The emphasis of this work is on the treatment of peak-size distributions of SXR flares and SPEs. The frequency of SXR flares and solar proton events (>10 and >100 MeV, respectively) for the past three solar cycles has been found to follow mainly a power-law distribution over three to five orders of magnitude of fluxes, which is physically correct beyond the "sensitivity" problem with the smallest peak values. The absence of significant spectral steepening in the domain of the highest peak values demonstrates that during the period considered, lasting 30 years, the limit of the highest flare's energy release has not yet been achieved. The power-law exponents were found to be −2.19 ± 0.04, −1.34 ± 0.02, and −1.46 ± 0.04, for the total SXR flare distribution and the total SPE distributions (for both E P > 10 MeV and E P > 100 MeV), respectively. For SPEs associated with flares located to the West of 20°W, the exponents are −1.22 ± 0.05 (E P > 10 MeV) and −1.26 ± 0.03 (E P > 100 MeV). The size distribution for corresponding flares follows a power law with a slope of −1.29 ± 0.12. Thus, X-ray and proton fluxes produced in the same solar events have very similar distribution shapes. Moreover, the derived slopes are not incompatible with a linear dependence between X-ray flare power and proton fluxes near the Earth. A similar statistical relation is obtained independently from the direct comparison of the X-ray and proton fluxes. These all argue for a statistically significant relationship between X-ray and proton emissions.

Gamma-ray emission extending to energies greater than 2 GeV and lasting at least for two hours as well as 0.8-8.1 MeV nuclear line emission lasting 40 rain were observed with very sensitive telescopes aboard the GAMMA and CGRO satellites for the well-developed post-flare loop formation phase of the 3B/X12 flare on June 15, 1991. We undertook an analysis of optical, radio, cosmic-ray, and other data in order to identify the origin of the energetic particles producing these unusual gamma-ray emissions. The analysis yields evidence that the gamma-rays and other emissions, observed well after the impulsive phase of the flare, appear to be initiated by prolonged nonstationary particle acceleration directly during the late phase of the flare rather than by a long-term trapping of energetic electrons and protons accelerated at the onset of the flare. We argue that such an acceleration, including the acceleration of protons up to GeV energies, can be caused by a prolonged post-eruptive energy release following a coronal mass ejection (CME), when the magnetic field above the active region, strongly disturbed by the CME eruption, relaxes to its initial state through magnetic reconnection in the coronal vertical current sheet.

Abstract.A new catalogue of 253 solar proton events (SPEs) with energy >10 MeV and peak intensity >10 protons/cm 2 .s.sr (pfu) at the Earth's orbit for three complete 11-year solar cycles is given. A statistical analysis of this data set of SPEs and their associated flares that occurred during this time period is presented. It is outlined that 231 of these proton events are flare related and only 22 of them are not associated with Ha flares. It is also noteworthy that 42 of these events are registered as Ground Level Enhancements (GLEs) in neutron monitors. The longitudinal distribution of the associated flares shows that a great number of these events are connected with west flares. This analysis enables one to understand the long-term dependence of the SPEs and the related flare characteristics on the solar cycle which are useful for space weather prediction.

82 gamma ray bursts were detected between 1978 September 14 and 1980 February 13 by the experiments of the interplanetary network (Prognoz 7, Vanera 11 and 12 SlOtiB experments, Pioneer Venus Orbiter, International Sun-Berth Explorer 3, Helios 2, and Vale). 65 o£ these events have been localized to annuli or error boxes by the the method of arrival time analysis. The distribution oE sources is consistent with isotropy, and there is no statistically convincing evidence for the detection oE more than one burst from any source position. The localizations are compared with those of two previous catalogs.

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