Re: I saw ISS!

From: C. Bassa via Seesat-l <seesat-l_at_satobs.org>
Date: Mon, 6 Apr 2020 15:24:11 +0200
Hi Patrick,

On Mon, Apr 6, 2020 at 3:08 PM Patrick Schmeer <pasc1312-seesat_at_yahoo.de> wrote:
> I still think Cees' city lights hypothesis is wrong.

I politely disagree.

In my earlier post, I already ruled out your first two hypotheses; 1)
Earthshine and 2) moonlight for the 22:53UTC observation on March
23rd. Here is the observation I posted earlier:
https://i.imgur.com/zws7dQz.png

To re-iterate; it was new Moon on March 24th, so with the Sun below
the horizon, so was the Moon.

The plot at https://imgur.com/a/lz7hROz shows the location of ISS
above the Earth. The red line indicates the terminator, and the 3 blue
lines on the dark side indicate the loci of civil (-6 deg solar
altitude), nautical (-12 deg) and astronomical (-18 deg). Hence,
almost the entire footprint of the ISS (gray circle) is located deep
at night; only a small bit of it near Iceland overlaps with locations
between nautical and astronomical twilight. This essentially rules out
Earthshine.

You yourself mention that artificial lights on board ISS can be ruled out.

Hence your reasoning also suggests that city lights are the remaining
option. It is interesting to note that at 22:53UTC, ISS was at 60
degrees altitude from Paris, also known as the "city of light".
Furthermore, my observations showed that ISS was fainter around
22:56UTC when it was above the Alps, where there are significantly
less cities.

Regards,
    Cees
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Received on Mon Apr 06 2020 - 08:25:13 UTC

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