Iridium Flare; Colorado, USA, 27 Aug 97

Ron Lee (ronlee@pcisys.net)
Wed, 27 Aug 1997 06:01:16

I finally saw the "whopper flares" of the new iridiums (#24907-24903)
FRom a previous obs a few days I knew they flared a little in the low
northeast sky on northbound morning passes.  On the same passes, Paul
Maley had seen flares when the satellites where west of him (if I recall
correctly). Hopefully he saw the same passes this morning.

The first three (#24907, 24906, and 24905) flared to mag -4 or so.
Definitely brighter than Sirius (in the southeast sky).  The fourth,
#24904, I did not notice a significant flare but I was observing naked
eye by then so it may have flared to a lesser brightness.  The final
satellite, #24903, flared but only to -1 or so.  Magnitude on initial
sighting in the southeast was about 7.

Following is the report for #24907 in Craig's format modified to include some
of the info I suggested last night.

                 Sat    Sat     Sun    Flare   Observer   Sun Phase
   UT            Dir  AZ  EL   AZ  EL   Dur  Mag     UT Delta     Pass Az/El

11:00:45 08/27/97  N  018 16   63 -15  >10s  -4   RGL  -6  Unknown   88 51

Location 104.5614 W, 38.9478 N, 2073 m

I like the line format better than the vertical one I suggested last night
but the max az/el, sun phase angle and UT offset are also of value as is the
satellite designation not on the line.  All essential info is there however.
The "Pass Az/EL" is the maximum elevation (and associated azimuth) of that
pass.

The iridium Delta rkt (#24908)  was about magnitude 2.  Possibly a contender
for the Visual.tle file.  It did dim as it went past the zenith but was 
still naked eye brightness.

Ron Lee