Monday, May 31, 2021

NGC 4395 (2021) and Processing Tutorial

Located approximately 14 million light-years from Earth in the constellation Canes Venatici is the beautiful spiral galaxy (also designated as a dwarf galaxy) NGC 4395.  It is 50,000 light-year across and is unique in that it has low surface brightness considering its proximity to Earth.  NGC 4395 has an active galactic nucleus (ANG) which means radiation is produced by matter falling into a central black hole, however, it is six times smaller than our own galaxy's AGN.  These types of galaxies are known as a Seyfert Galaxy.  It is one of the most faint nearby Seyfert galaxies known but it does have three bright nebulous regions, NGC 4399, NGC 4400, and NGC 4401, located on the spiral arms. 

This galaxy is in a good location for imaging in the Northern hemisphere but is not imaged much likely due to it's low surface brightness.  For this image I collected three hours of luminosity alone and tried to capture 1.5 hours for each RGB channel.  I collected much more data but I was very selective on which subframes to use.  Also I believe my luminosity filter is defective as I have been getting artifacts on my images for a long time now that has been a pain in the you know what to remove.  I cleaned the filter a while ago and did notice film thing but did not think it was a problem until now.  So, rather than purchase a new one - I just shot without any filter since I am not sure what they do anyway.
  
If you do attempt to image NGC 4395 I would recommend collecting a minimum of three hours of luminosity as it is a relatively galaxy for being so close.  

I have also attached my processing flow that I used for this image.  The PixInsight portion is standard to most of my images but once I get it to Photoshop, it turns into a pinch of this and dash of that.  The numbers in parenthesis are times that correspond to a video. Link: https://www.youtube.com/watch?v=Ma0x1aMcFDs 

Preprocess

  • PixInsight

  1. Blink - visual subframe inspection (3:23)

  2. SubframeSelector (3:40)

  3. Blink - visual final subframe inspection (4:26) 

  4. Weighted Batch Pre-Process - stacking (4:46)

 

Processing

  • PixInsight

  1. Dynamic Crop (5:53)

  • RGB

  1. ChannelManagement > ChannelCombination - combine RGB (6:12)

  2. BackgroundModelization > DynamicBackgroundExtraction (and/or Automatic) (6:12)

  3. NoiseReduction > TGVDenoise - reduce noise (6:47)

  4. NoiseReduction > MultilinearTransform - reduce noise (7:33)

  5. IntensityTransformations > HistogramTransformation - make nonlinear image (8:09)

  • Luminosity

  1. BackgroundModernization > DynamicBackgroundExtraction - smooth image (8:42) 

  2. Deconvolution - sharpen & brighten (9:02)

  3. NoiseReduction > TGVDenoise - reduce noise (9:56)

  4. NoiseReduction > MultilinearTransform - reduce noise (10:29)

  5. IntensityTransformations > HistogramTransformation - make nonlinear image (11:04)

  6. MorphologicalTransformation (11:23)

  • Combine

  1. IntensityTransformations > CurvesTransformation - equalize background intensity of 

RGB and Lum visually (11.39)

  1. LRGBCombination (11:50)

[Not on video - IntensityTransformations > CurvesTransformation - equalize

background intensity of both versions of LRGB (max & partial)]

  • Photoshop

  1. Combine max galaxy with partial image (30%) (12:12)

  2. TopazDenoise (74%) (12:23)

  3. Curves (12:41)

  4. ColorRange > Select & Mask > Layer Mask (12:49)

  5. Select & Color (13:01)

  6. Channel Mix (13:18)

  7. Vibrance (13:31)

  8. Deep Space Noise Reduction (13:39)

  9. Star color (13:48)

  10. Select Bright Stars (13:56)

  11. ColorRange > Select & Mask > Layer Mask (14:01)

  12. Star color adjustment (14:11)

  13. Repeat to your liking (14:38)



NGC 4395
Dates: 5-11, 5-12, 5-13, 5-14, 5-16, 5-17, 5-18
Camera: ZWO ASI1600MM-Pro
Telescope: Astro-Tech AT115EDT 115mm Refractor Telescope
Barlow: None
Focal Length: 805mm
f/7
Focal Reducer: 0.8x AstroTech Field Flatterner/Focal Reducer
Mount: Orion Sirius
Filter Wheel: ZWO EFW 8 x 1.25"
Filter: ZWO L, R, G, B
Focuser: ZWO EAF
Autoguiding: ASI120 Mini attached to an Agena 50mm Guide Scope/ZWO 60mm Guidescope
Exposure: L 181 x 60, R 99 x 60, G 111 x 60, B 93 x 60
Gain: 139
Offset 21
Temp: 15 C
Processing: NINA, PixInsight, Photoshop, Topaz DeNoiseAI.

https://www.instagram.com/astroquest1/
http://astroquest1.blogspot.com/
https://www.astrobin.com/users/kurtzepp/collections/
http://youtube.com/c/AstroQuest1
Posted by at

No comments:

Post a Comment

Subscribe to: Post Comments (Atom)