North America & Pelican Nebulas in Cygnus
H-alpha-RGB CCD Image
This CCD image combines the H-alpha image as the luminance layer with a standard RGB color layer. Unfortunately, the quality of the color frames did not match that of the H-alpha frames and the lens used exhibits coma. The H-alpha image as a grayscale is here. Since H-alpha light is in the deep red part of the spectrum (656.3 nM) we can also substitute the Ha image for the red image and generate an Ha-G-B in the same way as an ordinary RGB. The effect of this substitution can be seen here (Ha-G-B) in rough form.
| Date | 2002-06-28 (H-alpha), 06-29 (RGB) |
| Optics |
Nikkor f/2.8 80-200mm zoom at 200mm, f/4 on on ST-10 XME/CFW-8a with Mandel Adapter; A-P 1200 GTO mount |
| Exposure |
H-alpha: 16 x 10 minute unbinned frames, Custom Scientific H-alpha filter. RGB: 5 x 5 minute 2x2 binned frames, SBIG filters. |
| Processing |
Ha: Calibrated and combined, then mild low pass DDP applied in MaxIm. RGB: Colors calibrated and stacked in MaxIm, then registered in RegiStar and color combined to RGB in MaxIm. Size doubled and then registered with Ha image in RegiStar. Ha and RGB combined, levels adjusted, and mild unsharp mask and blur applied in Photoshop 6. |