An event on 14 June 2012, observed with the radio telescopes UTR-2 (Kharkov, Ukraine), URAN-2 (Poltava, Ukraine), and NDA (Nançay, France) during a joint Summer campaign, is analyzed and discussed. The high solar activity resulted in a storm of spikes, and a storm of Type III bursts, Type IIIb bursts, and a Type IV burst observed in the decameter band. During the observed time interval, the average flux of radio emission changed twice. Using spikes as a tool for diagnostics of plasma parameters, we followed variations of the coronal temperature and the coronal magnetic field in the observed time interval. Thus, in frames of the model described in this article the observed decameter spikes' durations of 0.3 -1 seconds correspond to the coronal plasma temperatures of ≈ 0.1 -0.6 × 10 6 K. At the same time the spikes' frequency bandwidths of 25 -80 kHz give us the magnetic-field value of about 2 G. B N.V. Shevchuk mykola.shevchuk@rian.kharkov.ua V.N. Melnik Melnik@rian.kharkov.ua S. Poedts Stefaan.Poedts@wis.kuleuven.be J. Magdalenic

A large number of Type IIIb-III pairs, in which the first component is a Type IIIb burst and the second one is a Type III burst, are often recorded during decameter Type III burst storms. From the beginning of their observation, the question of whether the components of these pairs are the first and the second harmonics of radio emission or not has remained open. We discuss properties of decameter IIIb-III pairs in detail to answer this question. The components of these pairs, Type IIIb bursts and Type III bursts, have essentially different durations and polarizations. At the same time their frequency drift rates are rather close, provided that the drift rates of Type IIIb bursts are a little larger those of Type III bursts at the same frequency. Frequency ratios of the bursts at the same moment are close to two. This points at a harmonic connection of components in IIIb-III pairs. At the same time there was a serious difficulty, namely, why the first harmonic had fine frequency structure in the form of striae and the second harmonic did not have it. Recently Loi, Cairns, and Li (Astrophys. 790, 67, 2014) succeeded in solving this problem.The physical aspects of observational properties of decameter IIIb-III pairs are discussed and pros and cons of harmonic character of Type IIIb bursts and Type III bursts in IIIb-III pairs are presented. We conclude that practically all properties of IIIb-III pair components can be understood in the framework of the harmonic relation of components of IIIb-III pairs.

An unusual solar burst was observed simultaneously by two decameter radio telescopes UTR-2 (Kharkov, Ukraine) and URAN-2 (Poltava, Ukraine) on 3 June 2011 in the frequency range 16-28 MHz. The observed radio burst has some unusual properties, which are not typical for the other types of solar radio bursts. The frequency drift rate of it was positive (about 500 kHz s −1 ) at frequencies higher than 22 MHz and negative (100 kHz s −1 ) at lower frequencies. The full duration of this event varies from 50 s up to 80 s, depending on the frequency. The maximum radio flux of the unusual burst reaches ≈ 10 3 s.f.u and its polarization does not exceed 10%. This burst has a fine frequencytime structure of unusual appearance. It consists of stripes with the frequency bandwidth 300-400 kHz. We consider that several accompanied radio and optical events observed by SOHO and STEREO spacecraft are possibly associated with the reported radio burst. A model that may interpret the observed unusual solar radio burst is proposed.

On 2015 February 21, simultaneous observations of Jupiter's decametric radio emission between 10 and 33 MHz were carried out using three powerful low-frequency radio telescopes: Long Wavelength Array Station One (LWA1) in USA; Nançay Decameter Array (NDA) in France; and URAN2 telescope in Ukraine. We measure lag times of short-bursts (S-bursts) for 105-minutes of data over effective baselines up to 8460 km by using cross-correlation analysis of the spectrograms from each instrument. Of particular interest is the measurement of the beaming thickness of S-bursts, testing if either flashlight-or beacon-like beaming is emanating from Jupiter. We find that the lag times for all pairs drift slightly as time elapses, in agreement with expectations from the flashlight-like beaming model. This leads to a new constraint of the minimum beaming thickness of 2.66". Also, we find that most of the analyzed data abound with S-bursts, whose occurrence probability peaks at 17-18 MHz.

We report on the results of observations of a type IV burst by URAN-2 (Ukrainian Radio interferometer of Academy Scienses) in the frequency range 22 -33 MHz, which is associated with the CME (coronal mass ejection) initiated by a behindthe-limb active region (N05E151). This burst was observed also by the radio telescope NDA (Nancay Decameter Array ) in the frequency band 30-60 MHz. The purpose of the article is the determination of the source of this type IV burst. After analysis of the observational data obtained with the URAN-2, NDA, STEREO (Solar-Terrestrial Relations Observatory) A and B spacecraft, and SOHO (Solar and Heliospheric Observatory) spacecraft we come to the conclusion that it is a core of a behind-the-limb CME. We conclude that the radio emission can escape the center of the CME core at a frequency of 60 MHz and originates from the periphery of the core at frequency 30 MHz due to occultation by the solar corona at corresponding frequencies. We find plasma densities in these regions supposing the plasma mechanism of radio emission. We show that the frequency drift of the start of the type IV burst is governed by an expansion of the CME core. Type III bursts, which were observed against this type IV burst, are shown to be generated by fast electrons propagating through the CME core plasma. A type II burst registered at frequencies 44 -64 MHz and 3 -16 MHz was radiated by a shock with a velocity of about 1000 km s −1 and 800 km s −1 , respectively.