Tom, Some months ago SpaceX changed the orientation of most Starlinks in low orbit (below 550km) to 'edge-on' mode which meant their solarpanels were placed edge-on to the Sun when the spacecraft were visible from the ground and the Starlink is dark. However, this mode is only entered some time after launch (and from my own observations that can now be many weeks after launch - SpaceX seem more relaxed than before). Before the point in time they move to this edge-on mode they are in the so called 'open-book' mode with the axis through the panels aligned to the velocity vector. The spacecraft is rotated around the velocity vector axis so the maximum sunlight falls on the panel face. This rotation angle is being changed all the time so this condition is maintained and the batteries are charged. It just so happens that when you saw (from Waterloo) the L15 Starlinks entering eclipse they were moving almost _exactly_ away from the Sun-direction (in the WSW) and since the Sun was below the horizontal (at the spacecraft) that meant the panels were pointing almost directly towards the ground (and therefore towards you). So you were seeing the full sun-illuminated face of the solar panel and the Starlinks were very bright. I saw this phenomenon a month or so ago with Starlinks from a previous launch and they were really very bright (mag 0 at one point). If the Starlinks are not directly moving towards or away from the Sun then the panels are pointing towards the Sun (which is left of right of the spacecraft track) and not towards the ground and the Starlinks can be much fainter. Sorry if this wordy explanation isn't clear, there are some digrams of mine at https://sattrackcam.blogspot.com/2020/05/guest-post-modelling-of-starlink-trail.html that might assist. regards Richard On 14/12/2020 01:50, Tom Wagner via Seesat-l wrote: > > > This may have been asked before. > > I have found that seeing the Starlink trains – even a couple weeks after launch – has not been easy. Since they have sunshields I find them very faint and in fact, once, even when using 7 x 35 binoculars, I wasn’t able to see them between clouds, and that was at a high altitude. > > Now in the first week of this December suddenly people around the US are seeing the last launch and thinking they are UFOs. I saw L15 myself on December 5 and it was easy to see from when it came over my house near Lyra all the way to where they entered the earth’s shadow in the NE. I estimated their brightness as being about a magnitude 3, close to what HA predicted at that time. > > I’m wondering, are they more visible in the US now because of the sun’s angle this time of year? They did not appear to be flaring. > > Thanks, > > Tom Wagner > Waterloo, Iowa USA > > > Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Windows 10 > > _______________________________________________ > Seesat-l mailing list > http://mailman.satobs.org/mailman/listinfo/seesat-l > -- mob: 0771 858 8940 _______________________________________________ Seesat-l mailing list http://mailman.satobs.org/mailman/listinfo/seesat-lReceived on Mon Dec 14 2020 - 12:52:44 UTC
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