More on Iridium flares

Mon, 27 Oct 1997 08:27:16 -0600

As Bjoern points out, the Iridiums can be in lower parking orbits and still
flare. My suggestion was to look at the operational mean motion and assume
that once achieved, flaring is very likely to be guaranteed.

My first daylight Iridium flare was detected this weekend.  Using 1:24,000
USGS maps and SKYSAT and IRIDFLAR in tandem, I found a place nearby where a
near zero mirror angle was predicted for Oct. 25 at 23:22UTC. It had been
totally cloudy all day and within 15 minutes of flare  time the 3 layers of
clouds broke in the area of a predicted flare for Iridium 13 (elevation 40,
azimuth 207) with the sun 3 degrees above the horizon. I easily spotted the
flare for 2 or 3 seconds as it was in a marginally clear spot between two
banks of cirrus clouds.  The sky clouded over within 20 minutes after the
flare.  No way to estimate brightness as there were no other objects
visible, not even the sun.

Paul D. Maley
United Space Alliance
DO5/Cargo Operations
NASA Johnson Space Center
Houston TX 77058 USA

phone: 281-244-0208
latitude 29.5378 north; longitude 95.0868 west; altitude 6 m