NGC-7023, The Iris Nebula

Type: Bright Reflection Nebula

Constellation: Cepheus

Distance from Earth: 1,300 Light Years

About: Commonly known as the Iris Nebula, NGC-7023 is a reflection nebula in the Constellation Cepheus in the northern hemisphere. Surrounded by dark dust lanes, NGC-7023 is the designation for the open star cluster within the bright nebula. 

Taking this image with the Celestron EdgeHD8 and the ASI533MM Pro, with its 1″ square sensor, gave me a nice, narrow field of view. This allowed me to focus on the nebula’s center and highlight the opaque dust. 

Now for the over-the-top techie stuff regarding my processing workflow:

  • In my post-processing with Pixinsight, I utilized several scripts to achieve this result.  First, using the Weighted Batch Preprocessing script to calibrate, normalize, align, and stack the 198 individual images to master images of their respective filters.
  • After cropping out the residual artifacts from the integration with DynamicCrop, I used the first of  3 scripts from SetiAstro, the Automatic DBE script which performs a combination of Automatic Background Extraction, followed by a Dynamic Background Extraction process during which it reviews and calculates the best location to place of sample points within the image to remove gradient from the background. 
  • Performed a correct only of BlurXterminator to correct the star eccentricity. 
  •  I used the Image Solver script to restore the astrometric solution lost during the image’s cropping. 
  • Using the Channel Combination process to combine the Red, Blue, And Green channels into a color image
  • The next SetiAstro script used was FindBackgroundBeta to search and select the best possible area and create a preview used in the next step. 
  • Spectrometric Color Calibration was the next step, and using the preview created by the previous script as the Region of Interest in the Background Neutralization. 
  • A full BlurXterminator was done on both the Luminance and RGB images with Stellar Adjustments set at 0.50 for the Sharpen Stars, and for the Nonstellar Adjustments, Automatic PSF was checked and 0.50 for Sharpen Nonstellar. 
  • The third and final SetiAstro script used was the Statistical Stretch script. It performs a process using a combination of Generalized Hyperbolic Stretch and PixelMath to dynamically stretch the image from linear to nonlinear. I do this to both the color and luminance images.
  • Next, I use StarXterminator to screen and remove the RGB stars so I can work in it separately and again on the luminance layer. 
  • NoiseXterminator is used to remove the noise from both color and luminance nonlinear images.  The process is set at Denoise 0.90 and Detail 0.25. 
  • LRGB Combination process is used to add the Luminance channel to the RGB image to boost the detail of the overall image. I will do this to the RGB stars image as well.
  • An ACDNR lightness mask is created from a clone of the new LRGB image and placed on the original. Then I will boost the contrast using Local Histogram Equalization. I will use  a Kernel Radius of 40, Contrast Limit of 1.5, and Amount of 0.35. I may run this a few times to my particular taste based on the image. Here I ran it twice. 
  • I will then use the Curves Transformation process to boost the color, first using Chrominance, followed by some Saturation. I will then do the same to the stars-only image. 
  • Next, I will run SCNR to remove any green cast still lingering in the starless and star images
  • Another script I used for this image was the Dark Structure Enhance script to boost the detail of the dark dust clouds in the image. 
  • The last script I use is the ScreenStars script to combine the starless and stars only images back together.
  • I will then add the ICC profile and run the FindingChart process to generate a star chart of the target’s location in the night sky. The chart can be seen below. 

Imaging Project Information:

Imaging Telescope: Celestron EdgeHD 8″ Schmidt Cassesgrain

Imaging Camera: ZWO ASI533MM Pro

Mount: Ioptron CEM60

Guiding: Off-Axis Guiding using the Celestron OAG and ZWO ASI174MM Mini

Filters and Frames: 

  • Filter: L, Exposure : 180.00s, 66 Light frames, Bin 2×2, Gain 100
  • Filter: R, Exposure : 180.00s, 36 Light frames Bin 2×2, Gain 0
  • Filter: G, Exposure : 180.00s, 36 Light frames Bin 2×2, Gain 0
  • Filter: B, Exposure : 180.00s. 60 Light frames Bin 2×2, Gain 0

Accessories: 

  • Flat Calibration: Primalucelab Giotto 250
  • Focuser: Primalucelab Essato LP 2″
  • Weather Station: Pegasus Astro Uranus Meteo Sensor
  • Computer: MeLe Overclock 4C
  • Observatory: SkyShed POD XL1

Software: Acquisition – N.I.N.A  Preprocessing and  Postprocessing: Pixinisght

Acquisition Period: June 11, 12, 14, 18, 19 2024 

Total Integration Time: 10 hours