RE: Iridium Flares ground projection (fwd)

Gunnar Glitscher (GGlitscher@t-online.de)
Wed, 4 Feb 1998 03:37:16 +0100

RJ@RMATSC.RIEM.COM schrieb:
> The width and length of a perfect Iridium flare can be calculated as
> follows:
>
>     dist = distance from the observer to the sat
>     alt = angle from observers horizon to the sat
>     1/2 = angular diameter of the sun
>
>     width = dist * tan(1/2)
>     length = width / sin(alt)
>
> For an Iridium whose distance is 1200 km and 30 degrees
> above the horizon the flare width would be 10 km and
> length 20 km.
>
> Real flares are far from perfect however.  There is no sharp line
> between light and dark and the actual flare spot would be both
> larger and fuzzier.
>
> The velocity of the flare is much harder to calculate but it would
> be of the same order as the velocity of the spacecraft.
>
> 			Randy
>
>
> > -----Original Message-----
> > From:	
jmonseur%mail.cpod.fr%cds.plasma.mpe-garching.mpg.de@Mail.Riem.Com
>  [SMTP:jmonseur%mail.cpod.fr%cds.plasma.mpe-garching.mpg.de@Mail.Riem.Com]
> > Sent:	Tuesday, February 03, 1998 5:46 AM
> > To:	SeeSat-L%cds.plasma.mpe-garching.mpg.de@Mail.Riem.Com
> > Subject:	Iridium Flares ground projection
> > 
> > Good morning all,
> > 
> > To Rob.Matson,  Randy John  or anybody  knowing:
> > 
> > Could one see an Iridium flare  projection moving on the ground
> > or  on the sea, e.g. from a plane or from a cliff  ?
> > 
> > What would be its width ? its speed  relation with the sat ?
> > 
> > Many thanks.
> > jm
> > jmonseur@mail.cpod.fr    Tel. 0231 85 55 19
> > GPS  Lat. N. : 49d 11' 8.65"   Long. W. : 0d 22' 41.2" Alt. : 48 m
>