Re: Variations in Visibility of Starlink Passes - Question

Thank you all for your thoughts.  Ronlee's excellent detailed comments made me go back to look at my 4K video on the June 23, 2023 pass to look at those 5 trailing objects that I saw were much dimmer than the rest.  I guess that I sort of get it now.  They do something in the configuration or attitude of the satellite to minimize the brightness per Anthony Mallama's Sky & Telescope artic

Here is a 4K video clip that shows the trailing objects on June 23 very well if viewed in 4K and a bright full screen.

https://www.youtube.com/watch?v=1P9LuhNZMCA


Dan
> On 06/25/2023 3:16 PM CDT ronlee--- via Seesat-l <seesat-l_at_lists.seesatmail.org> wrote:
>
>
> 1)   Background:
>
> Launch of Starlink 5-7 was at 7:19 UT on 22 June 2023.
>
> Satellites deployment at 7:36 UT on 22 June 2023
>
> 2)  My first observation of the Starlink 5-7 satellites about
> 21 hours after deployment.
>
> Starting at 4:18 UT on 23 June 2023 I observed the Starlink 5-7
> train naked eye about 12 degrees elevation in the northwest.
>
> Max brightness before entering Earth shadow in Ursa Major was
> about 1.5
>
> Observing location Falcon, CO USA
>
> 3)   My second observation of the Starlink 5-7 satellites about
> 45 hours after deployment.
>
> Observed these objects again starting at 04:18 UT on 24 June 2023.
>
> Rising in the west-northwest just north of Venus.
>
> The leading 15 or so objects were much brighter than the remainder of
> the procession and that was obvious from near the initial sighting until
> they entered Earth shadow.
>
> Range at magnitude estimation point was 565 kilometers and phase angle
> 54.9 degrees yielding a standard magnitude of 1.6.  Magnitude estimate
> of the leading brighter objects was 2.
>
> 4)  Third observation attempt was around 4:20 UT on 25 June 2023.
>
> It was a low elevation pass in the west and I did not see a single
> satellite using binoculars.
>
> 5)  Assessment:  Somewhere I was under the impression that the change
> that resulted in much fainter satellites happened after two days
> on-orbit.
> I do not know where that duration came from.
>
> However, my second observation appears to be with that change in
> progress
> since the initial fifteen or so (not counted) were still bright but the
> trailing ones were much fainter.
>
> I did not mention it but as I was trying to get an magnitude assessment
> of the
> leading bright objects using 7x50 binoculars  (second observation), I
> was
> "seeing" some sort of brightness fluctuation in the fainter trailing
> satellites.
> In retrospect I should have concentrated on that.
>
> If anyone saw the 5-7 satellites hours prior to and after my 04:18 UT
> observation on
> 24 June 2023, it might provide useful information.
>
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