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

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5. Common events

5.1. Definition

We focus our attention on the events detected simultaneously by both receivers (NDA and Wind/WAVES). We consider as common events those observed simultaneously by both receivers, a gap of less than 30 minutes is accepted. We restricted the study to the morning data, so that the ground-based array is in the best conditions to record low frequency events as well. Among the events recorded in the morning about one half is observed by both radio receivers (52[FORMULA] for Wind and 47[FORMULA] for Nançay).

5.2. Properties of the common events

The common events are analysed as a function of the same criteria as the whole set of events. The results are summarized in Table 2. In the following we compare for each parameter the last column of Table 1a/1b (morning events) to the first one of Table 2a/2b (morning common events). If the percentage in Table 2 is greater than in Table 1, the concerned criterion increases the probability to be a common event. We compute in the last column of Table 2 the percentage of common events for each selected criterion. When this percentage is greater than 52[FORMULA] in the case of Wind/WAVES and 47[FORMULA] for Nançay, the considered criterion increases the chance for one event to be observed by both systems.


[TABLE]

Table 2. Morning common events recorded by Wind/WAVES (2a) and the NDA (2b).


In the case of Wind/WAVES data the arc curvature seems to be the only criterion which slightly increases this probability: in the last column of Table 2a 57[FORMULA] of the VEA are common. In the case of Nançay data several criteria play a role: the intensity, the frequency range (when emission is observed at frequencies lower than 15 MHz), the VEA-shape, the polarization (33[FORMULA] of the events have left-hand polarizations in the morning compared to 54[FORMULA] in the common data set). To evidence these results we have reported in the last column of Table 2, for all the criteria, the percentage of common cases among the morning events.

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© European Southern Observatory (ESO) 2000

Online publication: February 25, 2000
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