re: Nanosail-D2 best color result

From: Thierry Legault (
Date: Tue May 10 2011 - 20:44:59 UTC

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    Now, what about the shapes suggested by these images? We must not 
    forget that the sail dimensions are 3x3 metres (10x10 feet). At a 
    distance of 740km, this corresponds to an object of 1.5 m (5 feet) at 
    the distance of the ISS during a zenithal passage. On the following 
    image of the ISS, I have represented this dimension as a yellow 
    square just above the ISS:
    This size is smaller than the size of the EF (Exposed Facility) boxy 
    modules at the end of the Kibo lab (just above the yellow square). 
    Since none of Ralf Vandebergh's ISS images show each of these modules 
    with their shapes, or even simply separate them distinctly, there are 
    all reasons to doubt that the shape of the sail is real. All the more 
    that, as for the image of USA-129/KH satellite, we have no reference 
    image or data that could tell us the real orientation (and the real 
    color) of the sail at the moment of shooting.
    All serious imagers know that, to have a minimum of confidence in 
    "details" shown by such images, in any case one raw image cannot be 
    sufficient. Many raw images (dozens at minimum) must be combined and 
    they must show consistent details.
    The result presented here is very probably a combination of various 
    causes such as distortion due to turbulence, bumps of the telescope 
    during manual tracking, Bayer matrix sampling effects, noise, 
    compression, heavy processing etc., as illustrated in this page:
    At 12:37 06/05/2011, Ralf Vandebergh wrote:
    >The image set shows how the color tones actually exist in the image. 
    >Left is original color, right is auto-color correction, this process 
    >increases contrast between the subtle color dyes. 
    Thierry Legault
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