Re: Daytime Iridium Flares

Bjoern Gimle (b_gimle@algonet.se)
Mon, 9 Feb 1998 06:59:59 +0100

Mir16609@aol.com (Don Gardner) wrote
>
>A question for the people on the list who have seen daytime flares:  How long
>are they visible?  The evening and twilight flares that I've observed are
>typically visible at 1x for as long as 15 secs.   I'm hoping for about 5
>seconds for the daylight flare.
>
That is about right. If you set IridFlar to a -4.0 or -3.0 limit, and 3-line
output, you will get an approximate length. I had no problem finding my
first -7 flare at 48 degrees, using a compass and an adjustable carpenter's
angle with spirit level.

You have an easier situation, except that it is easy to overestimate high
angles. If you can't suspend a thin hanging wire above you, use a point
on a roof edge, or a protruding branch, and turn around below it to make
sure it does remain at what you think is 90 degrees.

I have been thinking if a polarizing glass / camera filter would improve
the situation. Around 60-120 degrees from the Sun, it would probably dim
the sky more than the flare, but you might need to block off distracting
surrounding sky light.


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