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Re: (meteorobs) Iridiums
Hi all,
-----Message d'origine-----
De : Wayne T Hally <meteors@eclipsedot net>
>Iridium is a "Constellation" of some awful amount (sorry SeeSat guys, but
>to meteor observers, this is still light pollution) [20 or 40 I think?]
The original number was 77 (it is also the atomic number of .... Iridium)
but now it went down to 66, 45 of which are already in orbit.
>communication satellites (for Digital Telephone Service I believe). The
>Solar collectors are aluminized, and when the sun hits it just right can
>produce bright flares from 5-15 seconds long, with a few as high as
Mag ->8.
The flares are not made by solar collectors (which are normally oriented
toward the sun so they cannot flare to you) but by the 3 main antennas of
the satellite. The geometry of the satellite and its 3D position in orbit
are very well known so it permits to have accurate forecasts for iridium
flares.
>They are (IIRC) in about 400 mile orbits, so have slower angular velocity
>that say the MIR or shuttle, and are, I think, below naked eye visibility
>the rest of the time.
I tried to see them naked eye but to no avail. I could see some of them in
binoculars (7x50) after a flare.
> Perhaps it would be in all of our meteor observer's best interest, to >try
and see at least one of the real bright ones, so we can hopefully >discern
them from stationary meteors...
I agree. Another reason, given by George Zay is to make good distiction from
reports done by non experimented witnesses who can think about UFO or either
make a fireball report.
I think every recent fireball report made by non experienced users should be
cross-checked with iridium flares. (I know, this is quite a big job)
>I believe Alan Pickup suggested that you can see them with binoculars
>after the flare, but I haven't had time to track one down yet....with the
>sites Jean-Christophe suggested, I will try and track them down And if >you
doubt the magnitude estimates, some sighting have been made during >the day
so it is real. I'm sure UFO reports will abound :-<
I already saw 1 daylight flare and it was not very sepectacular.
>Disclaimer, I am not terrible knowledgable about these sats; I have been
>lurking on the SeeSat mail list for a while learning. I am not 100% sure
>of all my facts, so if someone knows better, please correct me...this is
>all from an overloaded memory.
I tried to.
Clear skies
Jean-Christophe 'Papou' Millot - email : papou@canl.nc
Consultant en Technologies de l'Information - IT Consultant
B.P. 13581 98803 Noumea CEDEX
Nouvelle-Caledonie - New Caledonia (22d17S, 166d28E) UT+11
Tel/Fax/Rep : (687) 27 69 84 - Mobile : (687) 77 19 97