Table 1

Position angles (PA; measured counterclockwise from north) of the different sectors used in the analysis of the intensity variations in the arcs (see Fig. 4).

Name PA Name PA

Sector 0 320°–330° Sector 4 125°–150°
Sector 1 300°–330° Sector 5 65°–95°
Sector 2 255°–280° Sector 6 17.5°–35°
Sector 3 185°–215° Sector 7 0°–17.5°

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