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Geocentric Speed, km s-1

Figure 5. The distribution in speed of the sda shower meteoroids as determined by moving window scans of the radiant region with a window width of 2 kms-1. The profile is fitted by a Gaussian curve with parameters Vq = 40.4 kms-1 and ay = 4.9 kms-1.

Shower

(kms-1)

Ae

Radiant Centre (A — A0, ß)

Probe Size

cap

23.4±3.1

120° ± 10°

(181.2°, 9.8°)

sda

40.4 ±4.9

130° ± 15°

(210.2°,-7.2°)

Peak 1

43.0 ±4.6

312° ± 8°

(214.8°,-18.2°)

Peak 2

37.0 ±4.8

145° ± 15°

(330.8°,-13.8°)

dsx

31.3 ±4.1

186° ± 7°

(330.2°,-11.2°)

eta

65.1 ±7.6

46° ± 9°

(294.2°, 6.8°)

Definitions of meteor showers detected.

Table 1

Definitions of meteor showers detected.

3.1. Daily Motion of Parameters

As noted in the previous section, the average radiant position of a meteor shower experiences a linear daily motion generally parallel to the ecliptic. In order to remove this motion a central epoch is chosen and all data are reduced to this. Table 2 lists radiant motion measured for each of the five meteor showers under study, using every shower point in an uncertainty weighted linear least squares fit. The large number of shower meteors (~ 2 x 102 to ~ 2 x 103) in each case enables a good fit for many of the parameters to be obtained. Note the generally more pronounced daily motions in equatorial as compared with the ecliptic Sun-referenced radiant positions, thus justifying the choice of the latter for searches within the radiant space.

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