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    Re: SpaceX Starlink launch: photo celestial
    From: David Pike
    Date: 2020 Jan 15, 00:32 -0800

    Frank you wrote: I did wonder if that was what you meant, Dave. I was 50:50 on the possibilities, but I figured the other option was at least loosely navigation. 

    Sorry I didn’t make myself clear.  It was a little quiz, open to all.  My first impression on watching the video was that the birds were still singing happily while the rocket was blazing away.  Then the bangs started.  I timed the gap between the first indication of the explosion and the first of the bangs, and it came to 12.2 seconds.  If the speed of sound that day had been 1125fps the distance would have been 13725ft, about 2.6 miles, or about 4.2km.  I did think about looking at met records to see what the surface air temperature actually was at the date and time of the explosion to refine the speed of sound, but as there was no guarantee that the first puff off smoke was the time of the first sound, or that the vision was perfectly synched with the sound, I didn’t bother.  It was just a little exercise.  Similarly, I did look briefly at finding a bearing from the aspect of towers and tanks to work out a position, but I didn’t want to get fingerprints over my nice new monitor screens (I suppose I could have used prints).  Also, I wasn’t sure if Complex 40 had been rearranged after the fire.  Much of the metalwork would have lost its strength and needed replacing. DaveP

       
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