|Canon EOS 3, tripod
Sigma 105 macro
Fuji Provia 100F
f5.6, (21) 10 second exposures in same frame
Okay, so this is a little bit different approach to star trails. Instead of simply leaving the shutter open for a while, I instead programmed Canon's TC-80N3 Timer Remote Controller to capture 10-second exposures about 45 seconds apart if I remember correctly, for a single frame exposed 21 times. Once again, since the earth was rotating the stars produced dotted lines.
Except for right smack in the middle of the frame, where a blue dot sits cheekily at the end of a dimmer sequence. I really don't know what caused this. While I was actually doing this during a (supposed) meteor shower, the exposure was too long for this to be anything moving. It has the appearance of a moderately dim star, but to appear just once it would had to have shone for less than 90 seconds.
Or, been perfectly stationary. It is possible to capture geosynchronous satellites on film, the ones that we rely on for worldwide communications, and that's what I suspect this might have been. I cannot remember where in the sky I was aiming, but the flatness of the arcs does support the idea that it was close to the plane of the ecliptic, which is where all geosynchs reside. It was pretty late in the evening I believe, and satellites (unlike stars) have to reflect sunlight to be seen. For it to be this dim in what would have been 21 consecutive exposures in the same spot, it would have been far too dim to see with even binoculars. But was it far enough out to capture any sunlight at all while the sun was mostly on the other side of the earth?
I did a little trick and selected just the end points of each dotted line, to basically produce the starfield that the frame captured and see if I could pin down just where in the sky this occurred, but so far have not been able to match it to any point, even knowing roughly where I would have been pointing and using a good stellar plotting program (Stellarium.) The resulting image can be found here, with the suspect dot indicated, but of course it could have appeared once during any one of the 21 exposures, making that location somewhat inaccurate, or it could have been there the whole time while the stars moved.
If you're into the mystery, this was taken either August 13 or 14, 2007, about midnight Eastern Daylight Time, from a rough position of Lat 36.020° N, Lon 79.131° W. I'm almost certain now this was taken with the 105mm macro, giving it a roughly 19° field of view across the corners, and it should be fairly easy to plot north from the frame (perpendicular to the trails towards the upper right corner.)
And it's also possible it's a mere booger of the film emulsion, appearing like a star only through coincidence. This idea is supported by finding another example in a night exposure during a storm, when no stars were visible, but it seems odd that even at high magnification it would appear so much like the stars. If you have any ideas, feel free to contact me through this page.