On Tuesday 10 September at around 2130 GMT I took two pictures of the constellation Cygnus, which was almost directly overhead at the time. When the pictures were developed I saw what looked like a scratch on both of them.
However, on closer inspection I noticed that the scratch on the second started off where the first scratch finished, and the "scratches" were made up of dots. The relevant parts are enlarged above. The bright star is Deneb, and the America nebula is in the background except it was too faint to show up after I scanned it. The whole picture is reproduced below.
Now, I've occasionally seen the tracks of aeroplanes on my photographs () but they cross the entire print in the time it takes for the exposure to be completed.
I often see satellites, but they're usually steady dots of light, and they pass as quickly as planes. (Click here for an example.)
The pictures above have been enlarged during scanning and show approximately 1° x 1° of sky (North upwards). The exposures were 2 or 3 minutes, so a back-of-the-envelope calculation shows that if it is a satellite, it must take about 48hrs to orbit.
It can't be a satellite in a geosynchronous orbit (my house is nowhere near the equator), and other satellites are normally in a much lower and faster orbit. It could be a satellite or a tumbling piece of space debris which only caught the light for a brief part of the exposure, except the tracks are equally bright along their length.
My best guess is that this is a piece of tumbling space junk which has ended up in a high orbit. Or maybe they're alien visitors...
Technical details - Pentax ME Super mounted on motor-driven tripod, 50mm Chinon lens, 2-3 minute exposures at f/4.0, 400ASA Fuji colour print film. Tuesday 10 September 2002 at around 2130 GMT. Observed from a secret location somewhere in South Lanarkshire, Scotland (my back garden).
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