Radio Jupiter after Voyager: An overview of the Planetary Radio Astronomy observations

Jupiter's low frequency radio emission morphology as observed by the Planetary Radio Astronomy (PRA) instrument onboard the Voyager spacecraft is reviewed. The PRA measurement capabilities and limitations are summarized following over two years of experience with the instrument. As a direct consequence of the PRA spacecraft observations, unprecedented in terms of their sensitivity and frequency coverage, at least three previous unrecognized emission components were discovered: broadband and narrow band kilometric emission and the lesser arc decametric emission. Their properties are reviewed. In addition, the fundamental structure of the decameter and hectometer wavelength emission, which is believed to be almost exclusively in the form of complex but repeating arc structures in the frequency time domain, is described. Dramatic changes in the emission morphology of some components as a function of Sun-Jupiter-spacecraft angle (local time) are described. Finally, the PRA in suit measurements of the Io plasma torus hot to cold electron density and temperature ratios are summarized

Radio pulses from cosmic ray air showers - Boosted Coulomb and Cherenkov fields

High-energy cosmic rays passing through the Earth's atmosphere produce extensive showers whose charges emit radio frequency pulses. Despite the low density of the Earth's atmosphere, this emission should be affected by the air refractive index because the bulk of the shower particles move roughly at the speed of radio waves, so that the retarded altitude of emission, the relativistic boost and the emission pattern are modified. We consider in this paper the contribution of the boosted Coulomb and the Cherenkov fields and calculate analytically the spectrum using a very simplified model in order to highlight the main properties. We find that typically the lower half of the shower charge energy distribution produces a boosted Coulomb field, of amplitude comparable to the levels measured and to those calculated previously for synchrotron emission. Higher energy particles produce instead a Cherenkov-like field, whose amplitude may be smaller because both the negative charge excess and the separation between charges of opposite signs are small at these energies.Comment: 10 figures - Accepted by Astronomy & Astrophysic

A broadband FFT spectrometer for radio and millimeter astronomy

The core architecture, tests in the lab and first results of a Fast Fourier Transform (FFT) spectrometer are described. It is based on a commercially available fast digital sampler (AC240) with an on-board Field Programmable Gate Array (FPGA). The spectrometer works continuously and has a remarkable total bandwidth of 1 GHz, resolved into 16384 channels. The data is sampled with 8 bits, yielding a dynamic range of 48 dB. An Allan time of more than 2000 s and an SFDR of 37 dB were measured. First light observations with the KOSMA telescope show a perfect spectrum without internal or external spurious signals.Comment: Astronomy and Astrophysics, in pres

Radio Detection of Cosmic Ray Air Showers with Codalema

Studies of the radio detection of Extensive Air Showers is the goal of the demonstrative experiment CODALEMA. Previous analysis have demonstrated that detection around $5.10^{16}$ eV was achieved with this set-up. New results allow for the first time to study the topology of the electric field associated to EAS events on a event by event basis.Comment: 6 pages, 4 figures Proceedings of the Rencontres de Moriond, Very High Energy Phenomena in the Universe, La Thuile, Italy (March 12-19, 2005

Radio Detection of Extensive Air Showers with CODALEMA

The principle and performances of the CODALEMA experimental device, set up to study the possibility of high energy cosmic rays radio detection, are presented. Radio transient signals associated to cosmic rays have been identified, for which arrival directions and shower's electric field topologies have been extracted from the antenna signals. The measured rate, about 1 event per day, corresponds to an energy threshold around 5.10^16 eV. These results allow to determine the perspectives offered by the present experimental design for radiodetection of UHECR at a larger scale.Comment: 4 pages and 3 figures. To appear in the Proceedings of the 29th ICRC, Pune (2005

Voyager spacecraft radio observations of Jupiter: Initial cruise results

Jupiter's low-frequency radio emission were detected by the planetary radio astronomy instruments onboard the two Voyager spacecraft. The emission is surprisingly similar in morphology but opposite in polarization to the high-frequency Jovian radio noise that were observed with ground-based telescopes for more than two decades. Several possible explanations for the behavior of the low-frequency emission are examined, but none of them is completely satisfactory

Radiodetection of Cosmic Ray Extensive Air Showers

We present the characteristics and performance of a demonstration experiment devoted to the observation of ultra high- energy cosmic ray extensive air showers using a radiodetection technique. In a first step, one antenna narrowed band filtered acting as trigger, with a 4 $\sigma$ threshold above sky background-level, was used to tag any radio transient in coincidence on the antenna array. Recently, the addition of 4 particle detectors has allowed us to observe cosmic ray events in coincidence with antennas

Radio Detection of Cosmic Ray Extensive Air Showers: present status of the CODALEMA experiment

Data acquisition and analysis for the CODALEMA experiment, in operation for more than one year, has provided improved knowledge of the characteristics of this new device. At the same time, an important effort has been made to develop processing techniques for extracting transient signals from data containing interference.Comment: september 200

Planetary radio astronomy observations from Voyager-2 near Saturn

Voyager-2 planetry radio astronomy measurements obtained near Saturn are discussed. They indicate that Saturnian kilometric radiation is emitted by a strong, dayside source at auroral latitudes in the northern hemisphere and by a weaker (by more than an order of magnitude) source at complementary latitudes in the southern hemisphere. These emissions are variable both due to Saturn's rotation and, on longer time scales, probably due to influences of the solar wind and the satellite Dione. The Saturn electrostatic discharge bursts first discovered by Voyager-1 and attributed to emissions from the B-ring were again observed with the same broadband spectral properties and a 10(h)11(m) + or - 5(m) episodic recurrence period but with an occurrence frequency of only of about 30 percent of that detected with Voyager-1. During the crossing of the ring plane at a distance of 2.88 R sub S, an intense noise event is interpreted to be consequence of the impact/vaporization/ionization of charged micron-size G-ring particles distributed over a total vertical thickness of about 1500 km