Re: FW: Iridium Flare Image

Bjoern Gimle (
Tue, 9 Sep 1997 22:04:05 +0200

>> From: Neil Clifford <>
>> Subject: Re: FW: Iridium Flare Image
>> Date: Fri, 5 Sep 1997 18:30:55 +0100 (BST)
>> [ ... ]
>>    The photo was shot August 25. The Iridiums 22-26 passed through the
>>    field beginning at 11:02:16 UT and ending at 11:03:47. The tracks are
>>    ordered from top to bottom as 24907, 24906,24905,24904,24903. Local
>>    elevation 35 degrees azimuth 212, slant range about 912km.
Sue Worden :

>Many thanks to Paul Maley and Neil Clifford for making this image
>available on the VSOHP web site.  Remarkable!  :-)
>And now a question...  I see four roughly parallel tracks and one
>"oddball" track below and roughly perpendicular to those four.  Is
>that odd fifth track that of the fifth Iridium?  Surely not...?!?
>But if not, then what is it?
I have looked at Paul's JPEG above, and his Flare1.bmp and Flare2.bmp
at the same site/directory, and generated SkyMap charts approximating
the picture. (negative image)

The perpendicular tracks are in the direction of star motion (during
about 4 min.), and the brightest one approximately matches the
position of beta Ceti, and I've seen several tracks that match other
stars in the area. (There is a faint one just above left of beta -
at slightly lower declination) Alpha Scl is just above the chimney,
and one just below the flares.

If you want a higher resolution plot you can run
through SkyMap, or if you have PrintGL or LaserJet4 or better,
you can use

The tracks are a bit closer to beta Ceti on Paul's picture, and
the predicted times are about 50 seconds early, with the just
7-11 hour old elsets I used.

To make predictions match the picture better, I generated the
corresponding *26.* files (not the *.gif), and had to set
lat. +33.7, long. -94.1 to get the right values !
(But both look quite convincing)

The size of Flare1.bmp appears to be about 16 * 23 degrees, and SkyMap
gives more like a square picture, so there is some excess at the top
and bottom.

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