by MarkBour » Fri Sep 02, 2016 4:03 pm
So, there was a series of images during the day, all underexposed except for the one at noon (solar noon?), all with the camera in the same spot and facing straight south, and these were superimposed and projected on the upper half of the image. Then at night, the camera was just swung around to face north, and a lot more exposures were taken so that the star points almost look like tracks, but you can see the individual images not quite continuous (I like that choice!).
Nice planning to catch the ISS, I guess it truly did a "track" in just one or two of the exposures. An interesting thing is the star tracks near the horizon that do not circle the north pole. The line that divides between the tracks that circle the north pole and those that do not, does that correspond to the celestial equator? And the projection of a 180 degree view certainly messes with things ... the ISS track, for example, was probably a lot straighter in the sky, not much of an arc.
I've probably got some things wrong ... like NCTom said, describing the whole composition in detail sounds like a great learning opportunity.
So, there was a series of images during the day, all underexposed except for the one at noon (solar noon?), all with the camera in the same spot and facing straight south, and these were superimposed and projected on the upper half of the image. Then at night, the camera was just swung around to face north, and a lot more exposures were taken so that the star points almost look like tracks, but you can see the individual images not quite continuous (I like that choice!).
Nice planning to catch the ISS, I guess it truly did a "track" in just one or two of the exposures. An interesting thing is the star tracks near the horizon that do not circle the north pole. The line that divides between the tracks that circle the north pole and those that do not, does that correspond to the celestial equator? And the projection of a 180 degree view certainly messes with things ... the ISS track, for example, was probably a lot straighter in the sky, not much of an arc.
I've probably got some things wrong ... like [b]NCTom[/b] said, describing the whole composition in detail sounds like a great learning opportunity.