Re: "Norway event"

From: Alan Pickup (alan@wingar.demon.co.uk)
Date: Sat Nov 23 2002 - 07:26:43 EST

  • Next message: Michael McCants: "OIG Catalog Action Report for the week ending November 23"

    There is a report, plus video, at
    
    http://www.aftenposten.no/english/local/article.jhtml?articleID=442072
    
    There was no large object re-entering near this time, but this could not 
    have been a re-entry anyway. The reported duration of eight minutes is 
    much too long; even a duration of three minutes would be too long for a 
    re-entry observed from the Earth's surface and passing directly 
    overhead. Obviously, this object did not pass overhead and, if a 
    re-entry, should not have been visible for more than a minute or so.
    
    On any case, here is something seriously "not right" about the report. 
    At a local time of 14:15 local time on November 19, the Sun would have 
    been 6 degrees high in the south-south-west as seen from that location, 
    only a few degrees lower than it was at midday. It was not "late 
    afternoon" and nor should "dusk have been settling over southern 
    Norway". If the Sun had been in that position, and object tracked from 
    west to south, then it should have been visible in the video. It isn't. 
    Also, the sky does appear to be darker than you would expect if the 
    video had been taken in full daylight.
    
    In my opinion, the reported time is wrong. Yes, it is the time given on 
    the video frame, but do we know that it was set correctly? It is 
    possibly that the video was taken later, just after sunset when it 
    really was the beginning of dusk.
    
    I am 100% certain that this was an aircraft leaving a short-duration 
    condensation trail. If the time really was the beginning of dusk, then 
    an aircraft and its condensation trail in the south-western part of the 
    sky could still be illuminated by the Sun even though the Sun had set as 
    seen from the ground. The condensation trail would appear very bright 
    because of the effect of "forward scattering" of the sunlight in the 
    darkening sky, and exactly like it appears on the video. The scattering, 
    and the brightness of the trail, would have been greatest when the 
    aircraft was most nearly "lined-up" with the Sun (wherever it was, above 
    or below the horizon). You might only have been able to see the aircraft 
    itself through binoculars, unless it glints in the sunlight, and it 
    would be too far away for any noise to be heard. The fact that the 
    "con-trail" lasts for only a few seconds depends on local high-altitude 
    conditions.
    
    I get several reports every year about similar slow "re-entries" - 
    almost all of them are in the general direction of the Sun close to or 
    usually just after sunset or (like one a week or two ago from Scotland) 
    just before sunrise. On the evening before the recent Scottish report, I 
    saw the identical phenomenon (short duration con-trail showing strong 
    forward scattering) in the SW evening sky from Edinburgh, so I knew that 
    upper atmospheric conditions were favourable.
    
    
    Alan
    -- 
    Alan Pickup / COSPAR 2707:  55.8968N   3.1989W   +208m   (WGS84 datum)
    Edinburgh  / SatEvo & elsets:    http://www.wingar.demon.co.uk/satevo/
    Scotland  / Decay Watch: http://www.wingar.demon.co.uk/satevo/dkwatch/
              *
    
    
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