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Paper: The Inhomogeneous Response Across the Solar Disc of Unresolved Doppler Velocity Observations
Volume: 416, Solar-Stellar Dynamos as Revealed by Helio- and Asteroseismology: GONG 2008/SOHO 21
Page: 245
Authors: Broomhall, A.-M.; Chaplin, W. J.; Elsworth, Y.; New, R.
Abstract: Unresolved Doppler velocity measurements are not homogeneous across the solar disc (Brookes et al. 1978). We consider one cause of the inhomogeneity that originates from the BiSON instrumentation itself: the intensity of light observed from a region on the solar disc is dependent on the distance between that region on the image of the solar disc formed in the instrument and the detector. The non-uniform weighting affects the realization of the solar noise and the amplitudes of the solar oscillations observed by a detector. An "offset velocity," which varies with time, is observed in BiSON data and has consequences for the long-term stability of observations. We have attempted to model, in terms of the inhomogeneous weighting, the average observed offset velocity.
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