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Are these photographic artifacts of some kind and if so how would they occur? They are almost the same exact shape and size. It is a photo of the Kuiper Belt from the New Horizon space probe taken directly from NASA web site. If it is not a common photographic event then what could it be?

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  • $\begingroup$ They’re present only next to bright stars, so I would suppose it has something to do with imaging captor “bleed” of the light to neighbouring pixels… $\endgroup$ Jul 11, 2023 at 17:56
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    $\begingroup$ Looks like maybe the CCD is being read-out raster wise and the pixels following saturated pixels can't be read correctly. Looks like some of the less-saturated pixels have the same effect, but shorter. Also probably a lot of data compression going on with images from New Horizons. $\endgroup$
    – antlersoft
    Jul 11, 2023 at 18:03

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Weaver et al. 2020 discusses New Horizons LORRI instrument performance in detail. The introduction says:

The LORRI CCD incorporates anti-blooming technology to eliminate bleeding of the electrons along columns when bright targets saturate (i.e., when the signal in a pixel exceeds the full-well capacity of ∼80,000 electrons).

Otherwise the tails of bright stars would be white and blocky. Figure 5, another deep image of a star field, explains similar artifacts:

The brightest stars are saturated and have black tails due to amplifier undershoot.

Jenkins et al. 2010, section 2, addressed a similar issue for the Kepler mission:

The analog electronics chain exhibits memory, necessitating the application of a digital filter to remove this effect, called Local Detector Electronics (LDE) undershoot.

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