A Preliminary Analysis of StarLink #85 Flare Captured by Kevin Fetter on 04-19-2020 @ 01:02:01

From: Robert Herrick via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 20 Apr 2020 23:58:01 -0700
Kevin Fetter provided a great video with an embedded clock timer running to
the millisecond along with the satellite ID info on SeaSat-L, Vol. 74 Issue
23, Message #17 . This along with Kevin's location I was able to
reconstruct all of the geometries at the time of the flare, see attachment.

Because the satellite sub-point was sufficiently close to Keven's
location I used a flat earth for purposes of the attached diagram but a
full spherical earth was used to derive all of the geometries.

Although the sun had set at Keven's location, it almost came directly over
his location to illuminate the satellite at the time of the flare.
Therefore there had to be a surface orientated so as to reflect the sun
downwards to Keven's location. Furthermore, the surface could not have been
static as the flare lasted only about 1 second (as many of them are
observed to do). For a fixed surface on a satellite at the altitude of this
StarLink satellite, it takes 8 to 9 seconds for a secular reflection of the
sun to move across a point on the earth's surface. What is the cause of
this disparity in flare duration? Does this imply that the satellite, or
portion of it, is moving or rotating?

Two other observations. First, there was a second satellite in Kevin's
video above #85 and moving along with it, but was less bright and did not
exhibit any flaring. Second, the sun set on StarLink #85 at 01:06:06, just
4 minutes 5 seconds after the flare.

Any comments or corrections are welcome.



Link to Kevin's video:

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Received on Tue Apr 21 2020 - 01:59:26 UTC

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