In November, 2016 we were imaging the Horsehead/Flame region in Orion when we noticed something very unusual. As the individual 4 minute Luminance images were taken, we were seeing what appeared to be satellite trails running in almost the exact same location from frame to frame. This went on for more than 3 hours. Previous experience photographing this region from New York state showed nothing like this.
Looking in TheSkyX we discovered that from our location here in Thailand the Horsehead Nebula runs along a line filled with geosynchronous satellites – they remain positioned over one spot on Earth. Here is a screenshot from TheSkyX. The Horsehead is circled in green, and moving in the direction of the green arrow. Circled in purple are a huge number of dots in an almost straight line, the geosynchronous satellites.
Here is another screenshot from TheSkyX, this time showing our telescope/camera field of view, and showing 4 minute trails that would be left by these satellites as our telescope tracked the Horsehead across this field of non-moving satellites.
As you can see from these subs, this is exactly the issue we were experiencing when taking our images. The red arrows point to the satellite trails. Note these subs were taken at a different time than the screenshot from TheSkyX so the lines aren’t exact matches, but you get the idea. Our telescope is F/3.0, so very sensitive to even faint satellites. The blue arrows point to a repeating arc reflection, a separate issue.