Re: Re-entry over Melbourne Australia?

Robin Whittle (rw@firstpr.com.au)
Fri, 15 Jan 1999 20:16:00 +1100

Thanks to Tony Beresford, Jeff Hunt and Jake Rees for responding to my
hastily written newbie post.  I had never heard of Iridium flares nor
did I know they were in polar orbits, when I saw this object.

Thinking about it now, when I first saw it - before it was obscured by
trees - I saw it as a bright light travelling at a potentially
aircraft- or helicopter-speed, depending on how far away it was. 
However it was travelling horizontally and due north as far as I could
see, and aircraft don't have a light shining out downwards and to the
right, as would be required to explain the bright light I saw.  The
closest thing which came to mind was the Police helicopter - but this
was purely a light, and it faded over a few seconds.  It might have
been five seconds or so - two seconds seeing it and realising it was
moving and something I could not immediately recognise, then three or
so seconds as I watched it as closely as I could in the belief it was
something burning up.

When I first saw it I had a clear view against night sky.  If there
had been any evidence of a trail of sparks, then I am sure I would
have seen it.  I had never heard of light bouncing so brightly of a
satellite, so I figured it must have been something re-entering.

I have seen quite a few meteors (for a non-astronomer) and with the
brigher ones - which were moving a lot faster than this object (except
one) there was a clearly visible trail.  The exception was what I
believe was either space debris, or a very slow and almost perfectly
horizontal and west -> east meteor, which I observed leaving a trail
of sparks, changing colour and splitting in two directly above me,
over 8 or so seconds and covering a wide expanse of sky - at Fraser
Island in late 1973.  

If what I saw last night was anything burning up, then it was very
bright and I cannot imagine how I would have missed seeing the trail I
would expect it to leave.

Considering the lack of sparks, the S->N orbit, the definite
possibility of the sun glancing off a 40 degree inclined surface, the
horizontal path and the fact that there are a lot of Iridium
satellites up there, my current theory is that I saw a flare from an
Iridium satellite which was not predicted by the impressive software
at:

   http://www.gsoc.dlr.de/satvis/

Last night I looked at quite a few satellite and Iridium sites - but
not this one.  Thanks Jeff for pointing me to this site's
retrospective capability.  The site works back by up to 48 hours, and
I have placed a copy of the report it generated at:

   http://www.firstpr.com.au/temp/iridium-flare.html 

None of those reported times comes close to what I observed - so the
mystery remains unsolved.

- Robin Whittle


21 metre Sliiiiinky: http://www.firstpr.com.au/slinky/