Satellites - it's getting crowded in Earth orbit

On the evening of 9 and 10 January 2024, I pointed my telescope at the Orion Nebula M 42 and was very surprised at how many satellites crossed the field of view within just 3 hours. Particularly conspicuous was an apparent motorway of slightly lower declination below the Orion Nebula. After a little thought I came up with the explanation for this apparently particularly popular satellite orbit.


Satellite tracks in 3h exposure time

Of course: the reason for the seemingly hectic activity at the right-hand edge of the image at a declination of approx. -7° is of course the geostationary orbit, where numerous telecommunication satellites have their fixed position relative to the earth surface.


Approximate declination angle of the geostationary orbit for 50° geographical latitude


Image after plate-solve with equatorial grid overlay

As the Earth rotates beneath the stars and the telescope mount compensates for this rotation, the geostationary satellites appear to move across the field of view - and in relation to the stellar background, they do so. A timelapse of the exposures visualizes the effect:


Gif animation of single exposures showing satellites passing in front of constellation Orion

Exposure Data:
  • Newton f=430mm f/3.3

  • Camera Canon EOS 6Da ISO800

  • Exposure times:
    • 60x180s

  • total: 3h

  • Date: 09-11.01.2024

  • Location: Bad Kreuznach / Germany

  • Mount Skywatcher EQ8R-pro with Pegasus Astro EQMod

  • Guiding und Exposure Control: INDI / PHD2 / CCDCiel auf XUbuntu Linux

  • Image Processing: PixInsight, Video: ffmpeg