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Ursa Astronomical Association

NGC 7635, Sh2-157, Sh2-155, NGC 7380 - 28.9.2022 at 00.00 - 28.9.2022 at 03.00 Järvenpää Observation number 109656

Visibility III / V

Eemil Pietilä, Ursa (Etelä-Suomi)

Finally clear weather and free time happened to be on the same day... It had already been a month since the last time. And next time, you may have to wait a long time due to school rushes and fall weather.

This image shows broadband data from three hours ago of nebulae in the constellation Cassiopeia/Cepheus. Next time, when it's clear and I have time to film, I'll have to try to film narrowband data for this. Now the mists are slightly covered by the stars.

I was surprised by how well I managed to bring out the mists of the area with only three hours of exposure. The picture had gradients and strange vignetting that were difficult to correct due to light pollution. Even flat photos did not correct this vignetting. I don't know what caused it. I have never noticed/experienced such a thing before. Difficult gradients, on the other hand, were handled by making several iterations with PixInsight's DBE tool. First with bigger dots and finally with smaller ones. In total, I had to repeat the DBE eight times. The eighth time was DBE for the starless image and finally I attached the stars back to the image.

More similar observations
Additional information
  • Observation target
    • Deep space object
  • Designation
    • NGC 7635, Sh2-157, Sh2-155, NGC 7380
  • Constellation
    • Cepheus
  • Weather
    • Selkeä sää, paitsi yhden maissa oli hetken aikaa pilvistä. Nämä kuvat heitin suoraan roskakoriin.

  • Nebulae
    • Emission nebula info

      In an emission nebula the hot stars nearby cause the gas glow. This should not mix with reflection nebula, where the gas is only lit up by nearby stars.

      The appearance of a gas nebula is irregular, and the fainter parts of it need bigger instruments to be visible.


      Emssion nebulae in Cepheus. The bigger part is composed of the nebulae Cederblad 214 (Ced214) and NGC 7822. The lower round nebula is called Sharpless 170 (Sh2-170). Image J-P Metsävainio.


      The Orion nebula. Image Samuli Vuorinen.


      In this 4-degree-field there are emission nebulae Sh2-157, Sh2-158, Sh2-159, Sh2-161 and Sh2-162 (or NGC 7635 aka Bubble Nebula) and open clusters M52 and NGC 7510. Image Juha Kepsu.


      NGC 281 aka Pacman Nebula. The object is in Cassiopeia. Image J-P Metsävainio.


      NGC 896 in Cassiopeia is the tip of Heart Nebula (IC 1805). Image Timo Inkinen.

    • Reflection nebula info

      Reflection nebula is gas only lit up by nearby stars. It should not be mix up with emission nebula, where hot stars nearby cause the gas glow. But then reflection nebulae are visible in the same areas with emission nebulae. The appearance of reflection nebulae is irregular, and many of them need bigger instruments to be visible.


      Reflection nebulae are glowing blue around the stars of Pleyades. Image Juha Parvio.


      The blue glowing reflection nebula NGC 1333 around the bright star is in Perseus. Image Timo Inkinen.


      The bluish reflection nebula NGC 2023 is located lower left from the Horsehead Nebula. The Horsehead Nebula itself is a dark nebula in the front of red emission nebula IC 434. In the left side there is NGC 2024 aka Flame Nebula. Image Samuli Vuorinen.


      NGC 7538 in Cepheus is a combination of reflection and emission nebula. Image Timo Inkinen.


      Rflection nebulae (LBN 550, 552 and 555) and dark nebulae (LDN 1228) in Cepheus. Image Juha Kepsu.


      Reclection nebula vdB 141 in Cepheus. Image Tero Turunen.

Technical information

Equipment: Canon EOS 450D, Samyang 135mm f/2, Sky-Watcher EQM-35 Pro, NINA Direct Guider (every 5 photos)

Camera settings: ISO 1600, f/3.2, 120 sec x 90

Post-processing: PixInsight and Photoshop

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