Re: Milstar and Centaur

Jason Hatton (
Mon, 3 May 1999 13:54:17 +0200 (MET DST)

Phillip Chien wrote

>In any case the Milstar and Centaur will certainly be very interesting
>visual objects, even at medium latitudes.  Centaurs are extremely
>interesting objects to view, and there are only a handful of them at low
>altitudes in roughly circular orbits (Centaur 2, HEAO, SAX).  This
>particular Centaur is 14' in diameter in comparison with the 10' diameter
>ones used with Atlases.
>Currently no elements are available from OIG for either object so this
>looks like an excellent opportunity for the amateur observers to find these
>objects and amateur orbital mechanics community to derive the orbit.  I
>would be especially interested in looking at any element sets for search

All of the Centaur G' upper stages launched by Centaur IV's are currently
classified objects, so it is not possible to obtain elements directly from
OIG. I did observed one of these objects last year which had been found by
amateurs (I don't remember which one, I don't have my observing log at hand
at the moment). It was a good flasher, much like the Atlas Centaurs, but
with a sharp double flash in each period. It was flashing up to about
magnitude +8 at a range of 20,000km, so the Milstar Centaur could easily
reach naked eye brightness from it's low altitude orbit.

If somebody can guess a preliminary orbit, I would certainly have a go at
trying to make positional & flash measurements of this potentially
interesting object.

Best wishes & clear skies,


Jason Hatton
Hopital de l'Archet
Rte St. Antoine de Ginestiere
BP 79, 06202 Nice Cedex 03


email :

 43.667N, 7.223E, Alt 30M