Flare from Iridium 31 - New Year's eve

David A Irwin (david.irwin@vega.co.uk)
Mon, 5 Jan 1998 12:49:33 -0000

Dear all,

Below is an edited copy of a flare prediction from Rob's excellent =
Iridflar program.  This was my first flare siting attempt.  I thought I =
would start with the brightest prediction!

TLE used:
IRIDIUM 31
1 24950U 97051G   97364.08130919 +.00000059 +00000-0 +14156-4 0 01146
2 24950 086.3978 017.5506 0002749 050.7186 309.4250 14.34217514015456

Home position:
Latitude:  51.17810  Longitude:   -0.13750  Altitude:   80.0 m
Time Zone: UTC  +0.0 h

                  Range                        Peak Std    Maximum Flare
   Time    Azm El  (km)  Azm  Elev FlrAng Mag  Mag  Mag Latitude =
Longitude
-------------------------------------------------------------------------=
-
18:23:48.0 037 46 1039.2 259 -20.3  1.98  1.0 -8.1  0.8  50.7834   =
-0.1164
18:23:55.4 034 44 1067.2 259 -20.3  0.01 -8.0 -8.0 -8.3  51.1803   =
-0.1374
18:24:02.5 032 42 1095.8 259 -20.3  1.81  0.9 -8.0  0.6  51.5609   =
-0.1573

When I ran the prediction for New Year's eve it coincided with clear =
weather, no moon and evening (rather than morning) flare time.  I nagged =
some friends to come out in the car for a short drive to the 'maximum' =
center point which is in farmland nearby (they were getting ready for a =
New Year's party and the only stars they wanted to see were to be beer =
induced). =20

We got out of the car and stood in very dark conditions with good =
horizontal visibility for about 5 minutes until the predicted time.  Sky =
was mostly clear with scattered well defined small clouds.

About 80 seconds before the predicted pass we saw another satellite =
heading NNE and passing through the same position of the sky about mag =
2.5.

The Iridium flare was very bright and on time and position.  We were =
looking at the exact position in the sky - and at the predicted time =
there it was; beaming for about 10 seconds.  Looked as bright as a =
airplane landing light then faded and disappeared.  Can't give a more =
accurate brightness estimate, but way brighter the Venus.

Happy New Year all,

DAI