Observational Mishaps - Other Features

List of images in which the unexpected features are obviously not due the CCD or the electronics:

meteors, asteroids, satellites, etc.: thin trails across image.

vignetting by the guider probe or the finder camera: lightpath blocked in portions of the image, i.e., mostly round, light-deficient feature in some part of the image.

occulting dome dropout shutter: image illumination very different from previous images and from the flats.

condensation on the dewar window: bright filamentary structure or dark doughnuts towards the center of the image.

frost/ice on the dewar window (inside or outside): filamentary stucture similar to water condensation symptoms, or dark "fingers" on the outside of the field; dust doughnuts can appear especially dark. For some cameras (particularly electronically cooled ones), a bright ring can be seen which increases in radius as the condensation evaporates (if frost is on the inside of the camera window).

dead lady bug on the filter: dark, circular region in some part of the image which tends to move around due to motion of the telescope, the filter wheel, etc.

airplanes in the image: broad, bright, tire track-like features on the image.

ghost images of bright objects in the image: strangely shaped (ghost) images of stars in the field due to internal reflection; frequently encountered with Schmidt telescopes.

light leak in setup: brightness gradient across the field of view caused by external light source.

light leak in filter wheel: large scale, bright scattered light features all over the image.

misalignment of filter wheel: light deficient, large scale features (plus bright ones in processed images) in the outer parts of the field of view due to vignetting by the filter wheel.

IR problems: infrared image with multiple problems: circle shaped ghost images of bright star (small and large size), wavy interference patterns, stripe across image, and dark blotches.

You may also check out a list of all the compiled images, or go back to the main directory.