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180 240 300 360

120 180 240 300 360

Solar Longitude J2000, deg

120 180 240 300 360

Solar Longitude J2000, deg

Figure 3. A selected wavelet enhancement search of the antihelion region highlighting the Southern 5 Aquarids shower peak.

The Southern 5 Aquarids shower is clearly evident, appearing above the 99.99% level in both of the amplitude profiles for a period centred about A0 ~ 125°. The central radiant position of this shower experiences a "steady-state" occurring both in (A —Aq)m and in (3m over the active period. It is found, however, that the radiant position is not trustworthy as a primary indicator of shower activity. Because the sky area of radar sensitivity changes with season, the sporadic sources themselves move in systematic long-term patterns which may appear shower-like while true showers, such as the Southern <5 Aquarids, generally experience some daily motion in their ecliptic longitude with respect to the Sun. This motion, appearing as a non-unity (A - A0)M gradient in Figure 3, is unpredictable. It is therefore difficult to design a computer algorithm to automatically pick out these "steady-state" radiant position patterns: they are therefore used as secondary indicators of shower activity, lending credibility to a structure which is already considered significant due to a local maximum in the normalised amplitude profile.

An interesting point to note in the Southern S Aquarids profiles are the differences in the time periods over which the original profile appears to be significant as compared to the normalised profile. The latter is corrected to a longer period due to the lower background activity experienced to each side of A0 £ [120°, 130°]; this is in better agreement with that expected from the corresponding radiant position "steady-state".

Additionally in Figure 3 a peak significant at the 99.99% level appears about Ae ~ 315°. The meteors producing this peak are not found to coincide with any known shower. It is an open question as to the reality of this shower candidate—it is possible that this is simply a particularly favourable alignment of the radar-Earth platform with the sporadic background. Further investigations on this candidate's characteristics are carried out in the second paper in this series..

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