Re: Iridium Rocket Obs, and Question

Bart De Pontieu (
Sat, 21 Feb 1998 15:15:45 +0100 (MET)

On Sat, 21 Feb 1998, Ron Lee wrote:

> I just observed the Delta rocket from the recent Iridium launch
> and am perplexed.  My first obs a few mornings ago (19 Feb) had
> an object that I thought was the rocket spinning at about twice
> per second.   This morning, the rocket was steady at about magnitude
> 3-4.
> The picture that I took of the Iridium flares has two good flares
> and four fainter steady tracks.  I did not understand why one of the
> tracks was not dotted (from a flashing satellite).
> This suggests that I mistook another currently UNID flasher for the
> rocket body on 19 Feb.

A rocket body can be tumbling end-over-end and look steady on one
particular pass. This will happen if you're looking along the rotation
axis. The next pass your viewing angle will be different and it will flash
again. Zenit rocket bodies were famous for this behaviour, one could see
it happening during one pass.