Astronomy Picture of the Day

    Discover the cosmos! Each day a different image or photograph of our
      fascinating universe is featured, along with a brief explanation
                    written by a professional astronomer.

                               2019 October 14

                         Andromeda before Photoshop
                         Image Credit: Kees Scherer

   Explanation: What does the Andromeda galaxy really look like? The
   featured image shows how our Milky Way Galaxy's closest major galactic
   neighbor really appears in a long exposure through Earth's busy skies
   and with a digital camera that introduces normal imperfections. The
   picture is a stack of 223 images, each a 300 second exposure, taken
   from a garden observatory in Portugal over the past year. Obvious image
   deficiencies include bright parallel airplane trails, long and
   continuous satellite trails, short cosmic ray streaks, and bad pixels.
   These imperfections were actually not removed with Photoshop
   specifically, but rather greatly reduced with a series of computer
   software packages that included Astro Pixel Processor, DeepSkyStacker,
   and PixInsight. All of this work was done not to deceive you with a
   digital fantasy that has little to do with the real likeness of the
   Andromeda galaxy (M31), but to minimize Earthly artifacts that have
   nothing to do with the distant galaxy and so better recreate what M31
   really does look like.

                    Tomorrow's picture: the galaxy above
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.

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