Harold, Once when I was watching the EGP satellite sparkling along, I saw what I believed to be an occasional red flash. It was nearing the earth's shadow when this happened. What was odd was that most of the flashes were still white. I was wondering if some diffraction ever takes place on the satellite. As with the red light of the sun being the last to penetrate our atmosphere at low altitudes, maybe only the red of an otherwise complete spectrum made it to me. Tom Iowa USA ----- Original Message ----- From: "Harald Edens" <edens@weather-photography.com> To: <SeeSat-L@satobs.org> Sent: Sunday, January 13, 2002 2:46 AM Subject: Re: Iridium flare was slow > Hello Tom, others, > > First, I'd like to quickly introduce myself to this group. I'm a graduate > student in physics, interested in weather and astronomy. I'm an occasional > satellite observer, mostly Iridium flares. My location is The Netherlands, > Wijdenes. > > I asked myself that question by Tom a while ago. The Iridiums move slower > because you look down their track (most of their velocity is away or towards > you if you see an Iridium low in the south or north, and the satellite does > not have much of a tangential speed w.r.t. you). > > I had an interesting observation, be it maybe hallucination but I am not sure. > I went out for a -8 flare 35d altitude, 155d azimuth. I saw it coming and > it created a corona in a cirrostratus veil. What was interesting is that it > slowly lit up, obtained maximal brightness (which I estimated only -5 or so, > so I thought it was due to the clouds). Then I saw (I think) a red flare, very > quickly (1/2th second or so) followed by more brightening and then the -8 flare. > Has anybody seen a similar event? it was Iridium 18 and its path of max. flaring > lay 1.5 km to the east of me. Maybe it was just a twinkling, and I saw only the > red part of the spectrum, like the twinkling Sirius does when it is low... but > at 35 degrees altitude? The weather was fair (save for cirrus). > > Thanks, > > Harald Edens > > NL, Wijdenes > 52d 37' 49.0" N > 05d 09' 25.5" E > > > > ----- Original Message ----- > From: "Tom Wagner" <sciteach1950@home.com> > To: "SeeSat" <SeeSat-L@blackadder.lmsal.com> > Sent: Sunday, January 13, 2002 7:54 AM > Subject: Iridium flare was slow > > > > Tonight I saw a -2 iridium flare that was about 30 degrees above the SSE > > horizon. It was one that was pretty late as far as iridium flares go. It > > seemed to brighten more slowly that what I am used to seeing. It also barely > > moved. > > > > Being quite ignorant of the geometry of these occurrences, can someone tell > > me if there are times when one can expect the flare to be more gradual and > > expect the satellite to move more slowly. Like, are the later ones more apt > > to be this way? > > > > Thanks. > > > > Tom > > Iowa > > USA ----------------------------------------------------------------- Unsubscribe from SeeSat-L by sending a message with 'unsubscribe' in the SUBJECT to SeeSat-L-request@lists.satellite.eu.org http://www.satellite.eu.org/seesat/seesatindex.html
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