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Astron. Astrophys. 354, 1101-1109 (2000)

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4. Characteristics of the events observed in the morning (00 UT to 06 UT)

The spectra recorded by the Wind/WAVES experiment have been analysed with respect to three criteria: intensity (percentage of very intense events), frequency range (percentage of events extending above 10 MHz) and curvature of arcs (percentage of vertex late arcs and vertex early arcs). We report in Table 1 the total number of events and corresponding percentage of events for the different characteristics in the case of all events (second column) and morning events (third column). In Table 1 the percentage of the very intense events are labeled as I=2. For NDA data the frequency range is separated in two parts (smaller/equal and bigger than 15 MHz), and another criterion has been added to describe the state of polarization of events with right-hand or left-hand polarization. A combined criterion (i.e. high intensity and left-hand polarization) is also given; the Table 1 is discussed in the next section.


Table 1. Spectral characterisation of the jovian events recorded during the same period by Wind/WAVES (1a) and the NDA (1b). The very intense events are those labeled as I=2 and the frequency listed refers to the highest frequency the event attained.

When considering all the events observed from ground and from space between 17 UT and 09 UT (see Fig. 2a and 2b), more than 50[FORMULA] are recorded in the morning between 00 UT and 06 UT. From space the number of events recorded in the morning is not much greater than what is recorded during the whole observing period (58[FORMULA]), this is in agreement with what we expected. On the contrary for ground-based observations 77[FORMULA] are recorded in the morning. At low frequencies 91[FORMULA] of the events where observed in the morning. The proportion of events observed at low frequencies is greater (67[FORMULA]) in the morning set of data than in the all events set (56[FORMULA]). For the other criteria the percentage is about the same order in both columns. In particular the VLA-curvature is more common than the VEA (about 73[FORMULA] of VLA arcs).

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© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000