IC-410 Nebula and NGC-1893 Star Cluster


IC-410 is an emission nebula in the constellation Auriga, and surrounds the open star cluster NGC-1893. The cluster is small and located in the top-center of this image. The nebula contains complex patterns of hydrogen, sulfur, and oxygen gas that glows when excited by radition from nearby stars. The two "tadpoles" appear to be early star-forming areas; it's interesting that their tails are both distorted in the same area and direction.

This narrowband image assigns Sulfur-II to the red channel, Hydrogen-alpha to the green channel, and Oxygen-III to the blue channel (this is the same palette used by the Hubble Space Telescope for its false-color images). I adjusted the colors in Photoshop to produce this result.

Celestron 9¼" at f/7.5 on a Losmandy G-11 equatorial mount
SBIG ST-8XM camera
SBIG CFW-10 filter wheel with Astrodon filters
Clement Bellerophon focuser
Guiding: 60mm f/5 refractor and ST-402 camera
Imaging and autoguiding with MaxIm DL 4.57
Red   (Sulfur-II) 3.3 hours (20 x 10 min.), unbinned, -25°C
Green   (Hydrogen-alpha) 3.8 hours (23 x 10 min.), unbinned, -25°C
Blue   (Oxygen-III) 3.3 hours (20 x 10 min.), unbinned, -25°C
Processing Dark and flat processing in CCDStack
Statistical-combined in CCDStack
Levels and curves, Neat Image, unsharp mask, and color-combinein Photoshop CS2
Date and Location 8, 9, 10, 11 & 16 Feburary 2007
Montpelier, VA    N 37° 49' 12", W 77° 42' 06"


This version of the image uses a different palette to approximate "natural color" by assigning Hydrogen-alpha to the red channel. Oxygen-III and Sulfur-II were assigned to the blue channel by layering the monochrome images and selecting a "Screen" blend. Once blended, the image was flattened, and the result was pasted into the blue channel of the RGB image. Then the green channel in the RGB image was synthesized from the red and blue channels.

Red   (Hydrogen-alpha) 3.8 hours (23 x 10 min.), unbinned, -25°C
Green   Synthesized from red (H-a) and blue (O-III + S-II) channels.
Blue   (Oxygen-III) 3.3 hours (20 x 10 min.), unbinned, -25°C
(Sulfur-II) 3.3 hours (20 x 10 min.), unbinned, -25°C