Re: Iridium 23 and 48

Bjoern Gimle (
Wed, 22 Apr 1998 09:46:28 +0200

>  I attempted a long exposure photograph of Iridim 48 which was predicted by
>GSOC to flare to Mag. -2.  I was pleasantly surprised to observe another
>satellite moving in tandem, separated by about 30 arcminutes.  This second
>satellite flared weakly (about Mag. +2) and should have been the highlight of
>my photographs so far.  I ran the numbers through Skymap and confirmed that
>Iridium 23 was the second satellite.  You can see a screen capture of the
>Skymap plot at (URL) 
>My question to the group is, what are the chances that I'll -ever- get a
>chance like this again?  I almost went over the counter after the photo
>technician.  If this was a "once in a lifetime", I may go back...
Ir48 is in a fairly typical spare orbit with MM .01 to .03 higher than the
operational ones. This means it will overtake one of them every 3-9 days,
and will be 30-90 seconds from the other, as an average, on the best pass.
There will be one such spare in each of the six orbital planes, so it will
be quite frequent, though rarely 30 arcminutes.

The larger separation doesn't make much difference to a still photo.

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