Flaming Star Nebula dark sky vrs city sky face-off

This is my third comparison of emission nebulae images. Broadband true color images under dark skies are the gold standard of amateur astrophotography. However most of us live under city skies. Broadband images of the planets and a few bright deep space objects can look good from under a light dome. Narrow band filters open up urban skies to colorful emission nebulae. In the past these images required monochrome cameras and expensive filter wheel setups. Now dual narrow band filters that pass light from Oxygen and Hydrogen are available which allow narrow band one shot color images by adding a single filter. These can be viewed in their native HOO palate or by enhancing white balance and color assignment emulate broadband or Hubble palate (SHO palate images).

This image below of the Flaming Star nebula and beautiful companions was taken from my garden in Austin, Texas, under Bortle 7 city skies on 2023-12-12 with 24 five minute images. WO RedCat 250/51mm, L-Ultimate dual NB filter 3nam Ha and O3, ASI533 MC camera, ASIAIR Plus controller, SW AZ-EQ5 mount. Processed in PixInsight, drizzle stacked then SPCC, RC-Astro Noise/Blur/StarXTerminator plugins, GHS, Curves, and PS final exp and crop

Right out of the camera these narrow band images are very red, Hydrogen heavy. Careful color balance adjustments can emphasize the blue-green Oxygen 3 and dimmed broadband white light for a more natural white balance.

For comparison the image below was made under the very dark skies (Bortle 2+) just north of Silver City, New Mexico. Exactly the same equipment was used except for the susbstitution of a UV/IR cut filter for the narrow band filter. The narrow band filter above cuts out about 97% of the city light pollution, but it also misses a lot of color imformation and dims the stars in the image. This is all visible in the broadband dark sky image below with 3.5 hours total exposure.

Buckaroo Banzai summed it up with "no matter where you go, there you are". As an astrophotographer its great to have the tools to take advantage of all kinds of locations and enjoy the beauty of the skies above.

Content created: 2023-12-15




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