Decided to go with a blend of OSH + Jimmy’s Royal Palette (math below) instead of a typical Hubble palette that I use for most of my SHO images. This photo is a 2 panel mosaic. Because M8 is fairly low declination, I had to use a laser to turn off the streetlamp at the end of my driveway while shooting it (more for the guidecam than for the main narrowband pics). Overall I’d consider this an improvement over my previous bicolor pic of the nebula from 2019.

Captured on April 24th and 25th, 2022, from a Bortle 6 zone.

Places where I host my other images:

Instagram | Flickr

Equipment:

  • TPO 6" F/4 Imaging Newtonian

  • Orion Sirius EQ-G

  • ZWO ASI1600MM-Pro

  • Skywatcher Quattro Coma Corrector

  • ZWO EFW 8x1.25"/31mm

  • Astronomik LRGB+CLS Filters- 31mm

  • Astrodon 31mm Ha 5nm, Oiii 3nm, Sii 5nm

  • Agena 50mm Deluxe Straight-Through Guide Scope

  • ZWO ASI-290mc for guiding

  • Moonlite Autofocuser

Acquisition: 4 hours 55 minutes (Camera at unity gain, -15°C)

Left Panel:

  • Ha - 10x300"

  • Oiii - 10x300"

  • Sii - 8x300"

RightPanel:

  • Ha - 12x300"

  • Oiii - 10x300"

  • Sii - 9x300"

  • Darks- 30

  • Flats- 30 per filter

Capture Software:

  • Captured using N.I.N.A. and PHD2 for guiding and dithering.

PixInsight Processing:

  • BatchPreProcessing

  • SubframeSelector

  • StarAlignment

  • Blink

  • ImageIntegration

  • DrizzleIntegration (2x, Var β=1.5)

Making the mosaic:

  • StarAlign left Ha panel to right (Register/union mosaic mode) to make master mosaic

  • StarAlign all panels from all filters to master mosaic (register/match mode)

  • GradientMergeMosaic to combine aligned panels into single mosaic image per filter

Linear:

  • DynamicCrop

  • AutomaticBackgroundExtraction

  • EZ Decon

  • NoiseXTerminator

  • STF applied via HistogramTransformation to bring each channel nonlinear

Combining channels into color photo:

  • ChannelCombination combine monochrome Ha Oiii and Sii images into a color image with OSH palette

  • PixelMath to make a second image using /u/JimmyTheChicken1’s Royal Palette

R = 0.3*Oiii+0.7*(Oiii^~(0.7*Ha+0.3*Sii))^1.2

G = ((Oiii*Ha)^~(Oiii*Ha))*Ha + ((Oiii*Ha)^(Oiii*Ha))*Sii

B = 0.9*Sii+Ha-Oiii

  • PixelMath to blend OSH and Jimmy pics together 60:40

Nonlinear:

  • LRGBCombination with stretched Ha as luminance

  • Stars extracted and saved separately using StarXTerminator

From here I duplicated the pic and exported one as a 32-bit tiff. From here I brought it into Photoshop and converted it to a 16-bit tiff using the ‘local adaptation’ mode. For some reason I kinda like the softer ‘dreamy’ look this gave it. Then I brought the photo back into PixInsight

  • Both images had some curve and SCNR green adjustments done to them

  • Separate stars image was also SCNR’d green, and added back to the images via PixelMath

  • PixelMath to combine the two separate nonlinear pics into a single pic 50:50 (will be the only one used going forward)

  • Extract L --> LRGBCombination for chrominance noise reduction

  • NoiseXTerminator

  • LocalHistogramEqualization

Two rounds of this. one at size 16 for the finer ‘feathery’ details and one at size 500 for large scale structures

  • Shitloads of CurveTransformations to adjust lightness, saturation, contrast, hues, etc.

  • EZ HDR at like 5% blend or something

  • DarkStructureEnhance

  • Resample to 75%

  • Annotation