This image shows three major astronomy objects:  The Lagoon Nebula (M8), the Trifid Nebula (M20), and Webb’s Cross (M21), all in the Milky Way’s Scutum-Centaurus Arm.

Webb’s Cross (designated as Messier 21 or New General Catalogue (NGC) 6531) is an open cluster of stars to the North East of Sagittarius.  M21 is a relatively young and tightly packed cluster of stars estimated to be about 4.6 million years old.  M21 has a magnitude of 6.5 and has a few blue giant stars, but is mainly composed of small dim stars, with a total of 57 stars.  The cluster is 4,250 light years from Earth.  This cluster of stars is significant because of its youth as a cluster, and the small variation in age in its stellar members.

The Trifid Nebula (designated as M20 or NGC6514) whose name means “three lobes” is a region of Hydrogen (H II) gas.  This object is fascinating, as it is a combination of an open cluster of stars, an emission nebula (the dense, reddish-pink portion), a reflection nebula (the blue portion), and a dark nebula (the dark “gaps” in the reddish-pink gas, which is designated as Barnard 85 (B85)).  The most massive star in this region (HD 164492A) is more than 20 times more massive than our own star, and is surrounded by a cluster of ~3100 young stars (in my photo, these are the bright stars in the center).  A lot of this data we now know based on Hubble Space Telescope and Spitzer Space Telescope analysis.

Emission nebulae are nebula formed of ionized gases that emit light of various wavelengths. The most common source of ionization is high-energy ultraviolet photons emitted from a nearby hot star, and likely in this case, a high HII region (hydrogen gas), hence the typical deep red color in the photo, where star formation is likely taking place and young, massive stars are the source of the ionizing photons.  Dark nebulae are so dense, that they obscure all visible wavelengths of light from being admitted.  In astronomy, reflection nebula are clouds of interstellar dust which might reflect the light of a nearby star or stars. The energy from the nearby stars is insufficient to ionize the gas of the nebula to create an emission nebula, but is enough to give sufficient scattering to make the dust visible.

The Lagoon Nebula (designated as M8 or NGC6523) is a giant interstellar cloud (emission nebula), and one of only two star forming nebula that can be seen with the naked eye (in very dark areas).  Within the nebula is an open cluster of stars (NGC6350).  The massive stars embedded within the nebula give off enormous amounts of ultraviolet radiation, ionizing the gas and causing it to shine brightly.  The dark areas are called Bok globules 3 distinct ones, which are dark, collapsing clouds of protostellar material (Barnard 88 (B88), B89, and B296).  Another feature is the Hourglass Nebula located near the center bright spot of the nebula.  In this area, fierce radiation from the supergiant star Herschel 36, a 9.5-magnitude star located immediately to the west of the Hourglass, both illuminates and whips its gases into strange spiral shapes.  The Lagoon nebula has a dimension of 110 by 50 light years and the nebula is approximately 5,200 light years from Earth.

A lot more detail can be read about this Nebula at the following website: https://skyandtelescope.org/observing/wallow-a-while-in-the-lagoon-nebula/

These pictures were shot with the ZWO Dual Narrowband filter which is great for heavy light pollution areas (like mine), bright moonlight, and allows light transmission in two main frequency regions:
1.     Hydrogen Alpha (Ha) (red) at 656.3 nm with a bandwidth of 15nm
2.     Oxygen III (Oiii) (blue) at 500.7 nm with a bandwidth of 35nm

I processed this image in three different color formats – One shot color (which is dominated by the red spectrum), Foraxx color scheme, which is one version of an HOO coloration (Hyrdogen Oxygen Oxygen), and a second HOO color scheme written by Star Over Jersey.  The HOO color schemes creates a blending of the Blue and Green channels of the RGB spectrum based on a combination of the brightest and darkest areas of the two channels to bring out the Oxygen spectrum – The Stars Over Jersey formula lends to more Teal images for the Oxygen spectrum.  The Foraxx color scheme often results in more “bronze-colour images, and was developed by “The Coldest Nights”, and I learned about it through many videos and the tools developed by Paulyman Astro. 

These images that make up this picture were collected on June 13th and 16th, 2023. The moon was basically a waxing crescent near the first quarter (~12.47% light).
My setup:·       

• Mount: EQ6R-Pro·
• Telescope: Williams Optics 81 mm Zenithstar doublet·
• ZWO-ASI290MM color camera with ZWO Off-Axis Guiding
• Hotech Corporation 2” Field Flattener·
• ZWO ASI2600MC Pro; Camera cooled to -10 deg C, with ZWO Duo-Band Narrowband Light Pollution Reduction Filter·
• Bortle-9 – South Los Angeles shot from my backyard·
• Integration Time: 6 Hours 15 Minutes; Lights (75 @ 300 seconds); Darks (20 @ 300 seconds); Flats (30) & Dark Flats (20)·
• Image Processing: Pixinsight – Using videos from multiple youtube teachers and website.  @ChaoticNebula, @Cosgrove’sCosmos, @ViewintoSpace, @EnteringintoSpace, @PaulymanAstro, @Lukomatico – Lots of great on-line teachers/examples.·
• Incorporated Russell Croman’s new BlurXTerminator – Amazing product

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Pixinsight Workflow Notes:
1.      WBPP with 3x drizzle (including cosmetic correction) – Based on typical local area seeing
a.      Includes dynamic crop
b.      Output Pedestal – Automatic; Preset - Maximum
c.       Lights – 75 (300 seconds) – 6 Hr 15 Min
d.      Darks – 20 (300 seconds) – 04/25/2023
e.      Dark Flats – 20 – 01/13/2023
f.        Flats – 30 – 07/08/2023

2.      Perform a Linear Fit (with Green as a reference) and recombine
3.      Resample – 70%
4.      Extract a Luminance Image
5.      Extract R, G, & B images  - Save OSC_Start
6.      DBE Subtraction for all OCS, R,G,B, and Luminance images – Used OSC as the reference point for DBE points

7.      OSC Image – Linear Processing
a.      Used Autocolor Script – Background Neutralization and Color Calibration
b.      SpectroPhotometric Color Calibration (SPCC) – Photo Flux (White Reference)                                                        
i.      Run Image Solver first                                                      
ii.      Save OSC_PreBlur
c.       BlurXterminator – With star reduction of 0.2 and Halo -0.1                                                        
i.      Used PSF Image script to find the best PSF diameter (plugged in manually) – Didn’t record number
d.      NoiseXterminator – 90% with detail at 0.15
e.      StarXterminator – Generated Star Image and Upscreen Stars
f.        Saved as OSC_Stars and OSC_Starless

8.      Lum, R, G, & B Images – Linear Processing
a.      BlurXterminator – With star reduction of 0.2 and Halo -0.1                                                        
i.      PSF Image Script: Red – 6.35; Green – 4.43, Blue 6.52, & Luminance 4.48                                                      
ii.      Lum – Checked Luminance Only
b.      NoiseXterminator – 90% with detail at 0.15
c.       StarXterminator – Generated Star Image and Upscreen Stars

9.      Stretched starless images with GHS_Script using the method described in Adam Block’s recent GHS Explained Youtube video. 
a.      For the OSC image, I centered the R, G, & B channel peaks relative to each other
b.      Star Images were stretched with Histogram transformation                                                        
i.      Small Curves Transformation for Saturation

10.   Non-Linear Flow
a.      Created two mask from the Stretched OSC image with the Range Mask script (and Bill Blanshan’s Mask Blur function) – Nebula and background Nebulosity (Mask 1) and Nebula Only (Mask 2)

b.      Luminance Image                                                        
i.      Subtle background darkening to reduce some of the background noise and 3 defects due to dust bunnies that weren’t fixed with my flats – I used Clone Stamp to help blend them with the background                                                      
ii.      Reversed mask – Increased overall color brightness subtlely                                                     
iii.      Unsharp Mask
1.      STD 4 with 80%

c.       OSC Image       
i.      Subtle background darkening to reduce some of the background noise and 3 defects due to dust bunnies that weren’t fixed with my flats – I used Clone Stamp to help blend them with the background                                                      
ii.      Reversed mask – Increased overall color and saturation                                                     
iii.      Color Masks – Red, Yellow, & Blue – Curves Adjustments to enhance colors                                                     
iv.      Tried to do LRGB with Lum Image but didn’t like so discarded LUM for OSC image                                                      
v.      Unsharp Mask
1.      STD 4 with 80%                                                     
vi.      Exponential Transformation (w/ Mask 2) – Increase nebulosity brightness (just slightly) – 0.2                                                   
vii.      Local Histogram Equalization (w/ Mask 2) – Basically increasing contrast
1.      Extracted Luminance – Used as a Mask2.      Different Settings
a.      32 – Contrast 1.5 @ 67%
b.      64 – Contrast 1.5 @ 40%
c.       128 – Contrast 1.5 @ 20%                                                  
viii.      Dark Structure Enchance Script                                                     
ix.      Final Noise Xterminator (with Mask 2) – 85%                                                      
x.      Added OSC Stars back in using Paulyman Astro’s formula

d.      FORAXX (HOO Image) 
i.      Created Oiii using Paulyman Astro’s formula                                                      
ii.      Created FORAXX Stars and Starless versions using FORAXX Utility                                                     
iii.      Used – Mask 1 and Mask 2 from above to subtle darken the background noise and fix dust bunnies (clone stamp)                                                     
iv.      Color Masks – Red, Yellow, & Blue – Curves Adjustments to enhance colors                                                      
v.      LRGB combination with Lum Image – Lightness at 0.55 with Chronomantic Noise Reduction                                                     
vi.      Exponential Transformation (w/ Mask 2) – Increase nebulosity brightness (just slightly) – 0.3                                                   
vii.      Local Histogram Equalization (w/ Mask 2) – Basically increasing contrast
1.      Extracted Luminance – Used as a Mask2.      Different Settings
a.      32 – Contrast 1.5 @ 67%
b.      64 – Contrast 1.5 @ 40%
c.       128 – Contrast 1.5 @ 20%                                                  
viii.      Dark Structure Enhance Script                                                     
ix.      Final Noise Xterminator (w/ Mask 2) – 80%                                                      
x.      Added Foraxx Stars back in using Paulyman Astro’s formula

e.      Stars Over Jersey (HOO Image)  
i.      Created Oiii SOJ version                                                      
ii.      Created SOJ HOO Starless and Star images  (Stars over Jersey - Carlos Valerino) 
iii.      Used – Mask 1 and Mask 2 from above to subtle darken the background noise and fix dust bunnies (clone stamp)                                                     
iv.      Color Masks – Red, Yellow, & Blue – Curves Adjustments to enhance colors                                                      
v.      LRGB combination with Lum Image – Lightness at 0.55 and Saturation at 0.47 with Chronomantic Noise Reduction                                                     
vi.      Exponential Transformation (w/ Mask 2) – Increase nebulosity brightness (just slightly) – 0.4                                                   
vii.      Local Histogram Equalization (w/ Mask 2) – Basically increasing contrast
1.      Extracted Luminance – Used as a Mask
2.      Different Settings
a.      32 – Contrast 1.3 @ 67%
b.      64 – Contrast 1.3 @ 50%
c.       128 – Contrast 1.3 @ 20%                                                  
viii.      Dark Structure Enhance Script                                                     
ix.      Final Noise Xterminator (w/ Mask 2) – 85%                                                      
x.      Added SOJ Stars back in using Paulyman Astro’s formula                                                     

11.   Final Color adjustments (very minor)
12.   Cropped picture & Annotated with my signature
13.   Output multiple picture types (jpg and png)