Re: HTV Observation First Orbit

From: Gerhard HOLTKAMP (grd.holtkamp@t-online.de)
Date: Fri Sep 11 2009 - 17:53:51 UTC

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    On Thursday 10 September 2009 20:41, Gerhard HOLTKAMP wrote:
    > The sky at my place cleared up just in time to see the HTV pass about 2
    > degrees above Jupiter at 18:17:58 UTC, 10-SEP-09. 
    
    After a good night's sleep and a look at the relevant Spacetrack TLEs I now 
    realize that I've actually seen the HTV and the booster on both the first and 
    second orbit without being aware of it. For those who like to know how to 
    fool yourself here is my story:
    
    With the sky still fairly bright at the time (Sun angle -5 deg) and the 
    expected magnitude of the HTV unknown I felt by best chance of seeing 
    something would be to look with a pair of 10x50 binoculars at Jupiter as HTV 
    should be passing slightly above this spot.  An object indeed passed at the 
    expected time and direction which thanks to my timing I now know was 
    2009-048B (the booster). I didn't notice any particular color or magnitude at 
    that moment
    
    I followed this object for a few seconds before sweeping back toward Jupiter 
    to check whether something was trailing but didn't see anything. Spacetrack 
    TLEs tell me that the HTV was 4 deg to the upper right of the booster and 
    just outside my field of view. I swept forward again to find the original 
    object and now I noticed the distinct reddish color and bright magnitude. 
    This was the actual HTV and it was the booster which was now just outside my 
    field of view. 
    
    The difference in color and magnitude should have told me right away that I 
    was looking at a different object but my mind was stuck with the idea of just 
    one object as I had expected the positions of booster and HTV to be 
    essentially along track rather than in elevation.     
    
    One orbit later I knew the HTV would rise almost vertically at an azimuth of 
    about 250 deg so I looked there with my binoculars. A weak spot was visible 
    slightly ahead of time and this must have been the booster. After following 
    it briefly I turned my attention to my camera and after that lost sight of 
    it. The booster actually entered Earth shadow 45 seconds earlier and at a 
    lower elevation than HTV. 
    
    I eventually picked up HTV as a bright reddish object shortly before shadow 
    ingress and my timing of it is consistent with 2009-048A. Once again my mind 
    was fixed on having seen just one object.
    
    Lesson Learnt: There is more out there than a narrow field of view will show 
    you!
    
    Gerhard HOLTKAMP
    Darmstadt, Germany
    49.8822N, 8.6558E
    
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