daylight iridium flare

richard.keen@kingsmarket.com
Sun, 08 Feb 98 17:56:14

                                  
 I Just observed a daylight Iridium flare, at 17:03 local time,
courtesy of the accuracy of Rob Matson's Iridflar program.  First, the
edited program prediction:
 Ir Date    Time    Az El  Range Node Sun     Ant Flar  Vis
              UT            km   Node  az elev    Angle Mag
 4 98-2-9 0:03:20.8 42 82  783.1  A   247 4.0  L  0.01 -8.4
 The sky conditions were far from perfect, with a milky veil of cirrus
and cirrostratus covering the sky and rendering the full moon faintly
visible.  I observed with a short focus 4-inch (10.8-cm) f/4 reflector
at 16x, aimed in azimuth by dead reckoning and in altitude with a plumb
line and ruler.  Despite the clouds, the Iridium 4 was obvious - even
brilliant - as it passed through the field of view (3 degrees).  It
took the Iridium about 6 seconds to traverse the telescope field, was
brightest pretty close to the center of the field (some luck here), and
was fading below visibility as it exited the field.  A magnitude
estimate of a brilliant object in a telescope through clouds would be
meaningless, but the predicted -8.4 does not seem out of the question.
 Now, I need to see one of these things at night!!!
 Cheers, Rich Keen
 Coal Creek Canyon, Colorado, USA (39.877N, 105.391W, elevation 2728m)