The Dolphin Head Nebula (SH 2-308) - 2025-01-31 - HOO Palette - Winter Star Party (Reprocessed)

Image published in the September 2025 edition of Sky and Telescope magazine.

 

Image:

This image is comprised of Ha and OIII band data, and for the first time I have a target where the OIII signal is far stronger than the Ha signal. In my rendering of this image that I posted a week ago, I could barely, if at all, see any evidence of the Ha in the image.

 

I altered my PixInsight workflow three ways to improve the original image and obtain this result. Before mapping the Ha and OIII to the RGB channels, I applied LinearFit to increase the intensity of the Ha data to match the OIII. After mapping Ha and OIII to the RGB channels, I applied SPCC, this time with Ideal QE Curve selected, and using Photon Flux for the Whte Reference. And lastly, I selected OIII as luminance when I mixed the colors in NarrowbandNormalization.

 

As a result of the alternate processing, I can see Ha depicted as a goldish color in the outlying wispy areas, and within the target object.

 

Equipment:

ZWO ASI6200MM-P/EFW 2" x 7 (HO)

TeleVue NP101is (4" f/4.3)

Losmandy G11

 

Software:

Captured in NINA

Processed in PixInsight

Finished in Affinity Photo

 

Integration:

Ha 20 x 600s = 3:20

OIII 26 x 600s = 4:20

Total integration: 7:40

Done