My First Dive into SHO: Capturing the Pelican Nebula with Duo-Narrowband and RGB
This is my first attempt at using the SHO (Sulphur, Hydrogen, Oxygen) palette, and I've combined duo-narrowband and RGB data to create this image of the magnificent Pelican Nebula. It's been quite a journey, going through seven different versions of this data and exploring new processing avenues in PixInsight.
The Processing Journey
A key breakthrough for me was extracting data from multiple channels simultaneously and utilizing color response charts to derive ratios. I believe I managed to pinpoint the absolute pixel response for my IMX533 sensor, which allowed me to develop specific formulas for pixel math to extract the data:
- Ha:
NB_R*0.7 + NB_G*0.15 + NB_B * 0.05 - Oiii:
NB_G*0.7 + NB_B * 0.45
For the Sulphur (Sii) channel, I creatively substituted with my RGB data, which yielded pleasing results.
- Sii:
RGB[0]*0.6 + RGB[1]*0.15 + RGB[2]*0.05
Imaging Details
This shot was captured using my Player One Ares-C telescope through an Apertura Carbonstar 150 from my light-polluted Bortle 8 backyard.
- Duo-band subs: Captured with the L-Ultimate filter, with a total integration time of 3 hours.
- RGB subs: Captured with the L-Quad filter, with an integration time of 1.5 hours.
The Result
Here is the final image:
I'm really pleased with how this turned out, especially given the challenges of processing in a Bortle 8 environment. It’s amazing what can be achieved with dedicated processing and a bit of experimentation!
What do you see in the nebula? Some viewers have pointed out interesting shapes like an elephant with a seahorse or even a smiling rabbit! I personally see the classic pelican shape when rotated 90 degrees counter-clockwise, with its head turned left and beak slightly ajar.
