Re: USA-129-KH perigee pass 09/10 high-res image

From: Thierry Legault (
Date: Tue May 10 2011 - 20:48:49 UTC

  • Next message: Marco Langbroek: "ISS over the sun"

    hi all,
    there are two problems with this image. First, we 
    have no reference image or data that would give 
    us just an idea of the real orientation of the 
    satellite at that moment and how its silhouette 
    would appear, therefore we have no information at 
    all that would help us to check if the image corresponds to any reality.
    Second, the raw image (the small dot in the 
    center of the frame) shows all the signs of 
    distortions due to turbulence or telescope 
    shaking on a point (or a very small) source, 
    and/or noise, as I have illustrated on this page:
    Atmospheric and instrumental artefacts on one 
    hand, and the absence of data about the real 
    silhouette of the satellite and the other hand, 
    gives all degrees of freedom to find, within the 
    thousands images of a video sequence, a lot of 
    them that may evoke a satellite, above all if 
    it’s enlarged 400% (four times) as here. But all 
    serious imagers know that, to have a minimum of 
    confidence in "details" shown by images of very 
    small objects, especially 8-bit compressed color 
    images taken with a bottom-of-the-range camcorder 
    such as the one used here (JVC GR-DX27E), 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 animation 
    shown above is far from sufficient, since it 
    contains only two consecutive frames, separated 
    only by 0.04 sec, so that the turbulence may well be correlated.
    In short, in the absence of such a consistent 
    series of raw images, in all likelihood the 
    contents of this image correspond to nothing real.
    At 18:06 06/05/2011, Ralf Vandebergh wrote:
    >subject: USA-129-KH perigee pass 09/10 high-res 
    >First result (long promised) of one of the 
    >favorable perigee passes of USA-129 over the 
    >past time. Shown is raw frame and processing. 
    >Don’t need to mention; Hubble-shape is 
    >Best regards, Ralf Vandebergh -------
    Thierry Legault
    Seesat-l mailing list

    This archive was generated by hypermail 2b29 : Tue May 10 2011 - 20:49:58 UTC