Bright Iridium 13 flare

Alexander Seidel (
Tue, 21 Oct 1997 12:43:33 +0200

I report on another Iridium flare of the "searchlight" category:

NORAD __date__ __time__ D azI eI azM eM azS _eS Phs Dur Mag Obs COSPAR
24840 97-10-21 05:03:20 N 005 48 096 89 096 -09 083  10  -6  AS 97030E

A comparably rapid increase in brightness was followed by a short (2 -
2.5 sec) flat brilliant maximum of bluish colour, and a somewhat slower
decrease of brightness to 1-power-invisibility again. Very impressive!

Minimum off-center mirror angle was predicted to be 0.34 deg (4 days old
TLEs), which according to the law of sines, along with elevation and
range parameters at the time of peak brightness, translates to a
distance of 8 km (5 mi) from my observing site to the centerline of the
pass, supposed the angle was true, i.e. the satellite was optimally

P.S. for those of you who wish to update their address books:
my email address has changed from "" to

N53.5932 E9.4683 6mASL