Galaxy Zoo Talk

Dots in square shape?

  • Krop by Krop

    What would you think those green dots in square shape could be? Forgotten focus cursor? 😃

    Posted

  • ElisabethB by ElisabethB moderator

    😄

    Those four dots are definitely an artifact. No idea what can produce this.

    Posted

  • KWillett by KWillett scientist, admin, translator

    The square shape and the fact that it appears in the J-band image only tells me that it had something to do with the dither. For one of the infrared bands we used (named J), the data comes from two separate exposures at the same wavelength, but moved around on the camera. This process is called dithering. We combine those two exposures to make the green channel in this color image; the square spacing shows an image artifact that didn't quite get removed.

    Posted

  • zutopian by zutopian

    It is funny, that the 4 dots in square look like the symbol for the UKIDSS images on the classification page. #artifact
    Here is an image, on which there are 2 squares. : : http://talk.galaxyzoo.org/#/subjects/AGZ0006tmx

    Posted