Decametric radio bursts associated with the 13 July 2004 CME event at frequencies 10–30 MHz

We report on the observations of solar type IV burst and its precursors on the 13 of July 2004 at frequencies 10 − 30 MHz. The radio telescope UTR-2 observational data compiled from SOHO, WIND, NDA, RHESSI, GOES data were used. The main properties (frequency drift rate, duration, flux) of type IV burst and its precursors, namely solar type III and type II bursts, are analysed. We consider the type IV burst connected with appearance of the coronal mass ejection, which occurrence coincides with the type IV burst beginning. Several physical characteristics of this CME were estimated

Frequency drift rates of powerful decameter Type III bursts

We report on the observations of powerful (fluxes are larger than 10⁻¹⁹ W m⁻² Hz⁻¹) solar Type III bursts at frequencies 10 − 30 MHz. Recordings of 163 bursts, observed in July 2002 and of 231 bursts observed in August 2002 are investigated. The main properties of these Type III bursts (frequency drift rate, duration, flux, frequency bandwidth) are analyzed. In present report we pay more attention to consideration of frequency drift rate. A great difference between the observed and the well-known empirical frequency dependencies of Type III bursts drift rate is determined. A linear approximation for the drift rate versus frequency is found. It indicates, that solar corona above active regions has exponential density distribution. We consider that drift rate value depends on the position of an active region on the solar disc

Sporadic solar radio emission at decameter wavelengths

Results of observations of the solar sporadic radio emission in decameter range are presented. These observations were carried out at UTR-2 radio telescope with 60-channel spectrometer and DSP (Digital Spectral Polarimeter) last years. Particular attention is devoted to such components of sporadic radio emission as Type III bursts, Type II bursts, “drift pair” bursts. New properties of these bursts, which distinguished for decameter band, are noted. They are as follows: – fine structure of Type III bursts unobserved before at other frequencies; – first discovered fine structure of Type II bursts in the form of small duration sub bursts with positive and negative frequency drift; – wavelike movement of Type II burst backbone with herringbone structure; – difference of frequency drift rates of “drift pair” bursts with positive and negative rates

New methods and equipment of decametric radio astronomy for continuum observation at the UTR-2 radio telescope

At present time the modernization of the giant decametric radio telescope UTR-2 is under way. New back-end facilities and methods which open up new possibilities for radio astronomical observations are developed. Some equipment was made in cooperation with Austrian and French radio astronomers. Current back-end facilities and methods used at the UTR-2 radio telescope are described and compared with former traditional methods, equipment and their characteristics. Some prospects regarding current progress in developing new generation of back-end facilities are also discussed. The main focus of the presentation is the observation methods and equipment applied at the UTR-2 radio telescope for the investigation of continuum radio sources: Galactic background, discrete sources (preparation for the catalogue of sources in the whole Northern Sky), SNR, HII regions. Some results of using the new back-end facilities (such as Digital Spectral Polarimeter) and processing methods are presented

Temperature variations in Titan's upper atmosphere: impact on Cassini/Huygens

Temperature variations of Titan's upper atmosphere due to the plasma interaction of the satellite with Saturn's magnetosphere and Titan's high altitude monomer haze particles can imply an offset of up to ±30K from currently estimated model profiles. We incorporated these temperature uncertainties as an offset into the recently published Vervack et al. (2004) (Icarus, Vol. 170, 91-112) engineering model and derive extreme case (i.e. minimum and maximum profiles) temperature, pressure, and density profiles. We simulated the Huygens probe hypersonic entry trajectory and obtain, as expected, deviations of the probe trajectory for the extreme atmosphere models compared to the simulation based on the nominal one. These deviations are very similar to the ones obtained with the standard Yelle et al. (1997) (ESA SP-1177) profiles. We could confirm that the difference in aerodynamic drag is of an order of magnitude that can be measured by the probe science accelerometer. They represent an important means for the reconstruction of Titan's upper atmospheric properties. Furthermore, we simulated a Cassini low Titan flyby trajectory. No major trajectory deviations were found. The atmospheric torques due to aerodynamic drag, however, are twice as high for our high temperature profile as the ones obtained with the Yelle maximum profile and more than 5 times higher than the worst case estimations from the Cassini project. We propose to use the Cassini atmospheric torque measurements during its low flybys to derive the atmospheric drag and to reconstruct Titan's upper atmosphere density, pressure, and temperature. The results could then be compared to the reconstructed profiles obtained from Huygens probe measurements. This would help to validate the probe measurements and decrease the error bars