Re: AMC-16 fuel dump observed - APOD

From: Ed Cannon (ecannon@mail.utexas.edu)
Date: Wed Feb 09 2005 - 00:17:56 EST

  • Next message: Alberto Rango: "4541 Satobs 5 - 6 - 7 Feb 2005."

    Pretty neat imagery!  Not surprisingly, I just had to think about 
    this one for a good while.  I was puzzled by the cloud being a 
    streak in the images and also why it didn't get wider over time.  
    After some research here and there, I found the answers.  Really 
    important are (1) the fuel dump occurred during ascent (increasing 
    height above the sub-satellite point) in the transfer orbit (I had 
    at first assumed it was a geosynchronous height, as we have seen 
    from here a time or two.) and (2) each image is a three-minute time 
    exposure.  So the result is that in each successive exposure, the 
    (very bright!) cloud is higher (Thus, the changing perspective due 
    to increasing distance accounts for it not expanding as would a 
    stationary cloud.) and moves through a shorter segment of arc.  
    
    At this location online are both Haleakala ("HL", on Maui) and 
    Mauna Kea (MK, on the "Big Island" of Hawaii) images taken at the 
    same times:
    
    http://bb.nightskylive.net/asterisk/viewtopic.php?t=291
    
    I found that looking at both sets of images was very helpful.  It 
    was not easy for me to pick out Leo in the HL images, but it's 
    pretty clear in the MK ones.  The cloud was certainly quite bright!
    
    On this page (p. 2), there's an eyewitness description (naked-eye 
    followed by telescopic observation) by "Guest" with the post 
    subject: "night sky weirdom" posted at 7:25 am followed a little 
    farther down by Randy John's (first?) post with the name "Skysat", 
    at 8:09 am with the post subject "AMC-16" (Sorry about the long 
    URL; if it breaks, the page is 2 of 12.):
    
    http://bb.nightskylive.net/asterisk/viewtopic.php?t=291&postdays=0&postorder=asc&start=15
    
    Kevin's (first?) post is on page 3 at 1:23 pm with the subject 
    "fuel dump from AMC 16 launch".
    
    Since Randy figured it out on page 2 with agreement from Kevin
    soon after, I'm just a little puzzled that there's still discussion 
    for 10 more pages....  
    
    Lots of clouds here recently, but worse lots of back trouble.  I
    haven't been satellite observing since January 8, but my back 
    seems finally to be really on the mend and so I'm hoping for 
    improving sky conditions as well.
    
    Ed Cannon - ecannon@mail.utexas.edu - Austin, Texas, USA
    
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