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Estimated beam of WMAP Q1 Differencing Assembly Map in Ecliptic Coordinate
Image Credit: Lung-Yih Chiang
Estimated beam of WMAP Q1 Differencing Assembly Map in Ecliptic Coordinate
Estimation of the effective inflight beam of WMAP Q1 Differencing Assembly in Ecliptic Coordinate. The bar denotes the asymmetry R= r_maj /r_min -1, where r_maj and r_min are the major and minor axis of the elliptical shape of the beam, respectively, and the orientation of the major axis is denoted by that of the bar.
Due to the scan strategy that the WMAP observes from a Lissajous orbit about the L2 Sun-Earth Lagrange point, and telescope line of sight is around 70 degs off the WMAP spinning axis, the path swept out on the sky by a given line of sight resembles a Spirograph pattern that reaches from the north to south ecliptic poles, hence the inflight beam pattern is closely related to the Ecliptic coordinate. Our results confirm that the inflight effective beams convolving the underlying signal are asymmetric for most parts of the sky, and are not randomly oriented. The alignment is most severe around Ecliptic Equator. Near the ecliptic poles, however, the asymmetry is small due to the averaging effect from different orientations from the scan strategy.
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