NGC 7129 – Reflection Nebula in Cepheus

NGC 7129 is a reflection nebula located in the constellation Cepheus. Located 3,300 light years away, NGC 7129 is a young open cluster of newborn stars. Many of the stars within the cluster are less than 1 million years old, which is very young when you consider many of these stars will live to be many billions of years old. The gaseous features are the left over ingredients for star formation.

NGC 7129 is a reflection nebula. Reflection nebulas reflect light from nearby stars while emission nebulas generate light from ionized gases. Reflection nebulas are images through red, green, and blue filters while emission nebulas are best imaged with narrowband filters (Sulphur-II, Hydrogen-Alpha, Oxygen-III).

NGC 7129 – Reflection Nebula in Cepheus

Imaging Details

  • Workflow: LRGB+HA
  • Red: 60*600 seconds
  • Green: 60*600 seconds
  • Blue: 60*600 seconds
  • Hydrogen-Alpha: 60*600 seconds
  • Binning: 1×1
  • Total Imaging Time: 40 hours
  • Imaging Dates: (8 nights)
    • 9/17/2021
    • 9/21/2021
    • 9/22/2021
    • 9/23/2021
    • 9/25/2021
    • 9/26/2021
    • 9/27/2021
    • 9/28/2021


From northern latitudes, NGC 7129 is located very high in the sky, making it an ideal target to image. Ideally, those looking to image the NGC 7129 should plan for the months of June through October. During that time, the nebula appears highest from the horizon.

Imaging Notes

Some quick tips about imaging NGC 7129

  • Data: This is the third image I’ve done where I did 10 hours per filter and the results are amazing. I’m thinking a good guideline for astrophotography is to focus on gathering more data on a fewer number of targets.
  • Exposure Length: This is the first image where I was able to use 10 minutes per frame with my red, green, blue filters. Previously, I would use 5 minute exposures. Based on the histogram, 10 minutes is my limit due to light pollution.
  • Luminance: I created a synthetic luminance by extracting luminance from the integrated RGB+HA image.
  • Hydrogen-Alpha: I captured10 hours of HA data, which was too much. In the center of the nebula, there is some HA signal, which, when mapped to the red channel, helps highlight those areas more.
NGC 7129 - Red
NGC 7129 – Red
 NGC 7129 - Green
NGC 7129 – Green
  NGC 7129 - Blue
NGC 7129 – Blue
   NGC 7129 - HA
NGC 7129 – HA