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Image Quality: Artifacts |
Welcome to http://www.handsonuniverse.org/activities/Explorations/HOUtips/artifacts/artifacts.html
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Image Quality: Artifacts |
If
suspected artifacts are present in one image of the same object but not
another image of the same object taken the same night only minutes apart,
then the artifacts are may be due to cosmic rays. Cosmic rays usually
affect only a few pixels and are sharply brighter than surrounding
pixels.
If suspected artifacts appear as irregular distinctly dark
pixels or groups of pixels on images of two different objects, then
the artifact is likely inherent in the ccd chip. Defects on the chip
are present in every image.
If suspected artifacts appear as dark donut shapes, they are
often due to dust inside the imaging camera or on the glass or filter
surfaces just outside the camera.
If image is generally gray and grainy in background, the moon or city lights may be brightening the sky background, there may be haze or thin clouds and/or the object may be low in altitude. When an object is low on the horizon, the telescope is pointing through a thick layer of atmosphere rather than up through the least amount of atmosphere. In all these cases, the brightness of the object being imaged is not much different than the brightness of the sky. Camera/chip imperfections are easily seen. The result of dust in the system, dust donuts, are also easily seen.
This streak is of unknown origin. Maybe it is from a satellite orbiting Earth. An airplane would probably be much brighter. Since it crosses an image that was taken over three minutes, it is probably not an asteroid since asteroids do not appear to change position so rapidly. It might be a meteor. It might be a satellite. So, here is a challenge for you to research.
