Re: UFO help?

Alan Pickup (alan@wingar.demon.co.uk)
Sat, 17 Apr 1999 11:54:42 +0100

>Monday night April 12th between 23:30 and 23:50 EDT (April 13th 04:30 to
>04:50 UTC) I saw what has been confirmed to me by the OIG as the re-entry
>of Cosmos 673 rocket (1974-066B/7418) beginning in an area of the sky
>approximately 20-25 degrees down to roughly 5-7 degrees off the horizon
>slightly to the north of Auriga. I marked the direction and compassed it
>later at close to 315 degrees NW.  

In my final report on this object in my posting "Decay watch: Apr 13", I
managed to include the wrong "final elset" for this. In fact the final
published elset was...
Cosmos 673 r     3.8  2.6  0.0  5.1 v            152 x 137 km
1 07418U 74066B   99103.19691916  .12875040 -99969-6  19007-3 0  9667
2 07418  81.1875 179.4923 0011715 264.8612  96.4247 16.48098688358399
Note that this epoch is close to a northbound equator crossing at 04:44
UTC on the 13th.

Using this elset, Mike McCants' LATLONG program gives the following
track when it passed closest to Neptune Beach...

          UTC   Height(km)    Latitude(N)   Longitude(W)

        04:49     147             23.5          89.9
        04:50     149             27.6          89.3
        04:51     150             31.7          88.7
        04:52     151             35.7          88.1
        04:53     153             39.8          87.3

This is not consistent with a re-entry during that pass. Could the final
elset be appreciably in error? It shows the rocket running 5 seconds
early against a SatEvo evolution through earlier elsets, which implies
it was decaying a little faster than SatEvo predicted. However, to force
the SatEvo evolution to decay during the pass, I would need to increase
the drag by a large factor, with the result that it would have been
running *another* 20 seconds earlier than is implied by the elset. I
think this is most unlikely. I would like to know the basis of OIG's
apparent confirmation of this re-entry.

My own analysis of the decay implied that it occurred at 08:14 UTC on
the 13th, with an uncertainty of +-45 minutes. SpaceCom's analysis was
that re-entry occurred within one hour of 08:37 UTC.

>
>Anyway, as 7418 broke up it appeared to split in two somewhere amidships. I
>can say that I saw the lower half melt-into itself and re-enter, but the
>second half may have been propelled back out. 

Re-entering objects often fragment, as do bright meteoritic fireballs
which I believe this was.

>
>Is it possible that this second half re-circulated then joined the first
>fracture at or near the same spot 40 odd hours later, or is there a chance
>that the date of the other observation is incorrect? 

It could not possibly have been "propelled back out" and re-circulated
for another 40 hours.

Alan
-- 
 Alan Pickup | COSPAR 2707:   55d53m48.7s N   3d11m51.2s W   156m asl
 Edinburgh   | Home:   alan@wingar.demon.co.uk    +44 (0)131 477 9144
 Scotland    | SatEvo page:     http://www.wingar.demon.co.uk/satevo/