About the Image:

I've been wanting to make a multi-panel mosaic of the Horsehead for some years, but I have always been held back by the fact that my Riccardi-Honders has a problem with really nasty reflections if bright stars are in or near the field of view.* Obviously, the Belt of Orion is rife with bright stars. Roland Christen has a fix in the works for this issue, but in the meanwhile I decided to address the problem by taking not just the 8 panels I needed, but also taking panels that were offset from the eight primary locations. That caused the reflections to move around enough that by combining data from offset frames, I was able to get "clean" images. 

These improved images worked well, except that the resulting gradients made getting a good mosaic extremely challenging. I ended up using a combination of photometric mosaic and gradient merge mosaic to get a final result. 

All panels were captured binned 2x2 since I didn't want to deal with the data and processing requirements of several thousand frames at sixty megapixels each.

Overall, a really challenging image to process, but I feel like the result was good. The primary goal was to capture a wider perspective of the Horsehead that included some of the Orion Molecular Cloud, particularly the swirling nebulosity below the Horsehead as well as the reflection areas above Alnilam.

In addition to the color image, I am also showing a blended luminance and H-alpha image that shows the swirling nebulosity well.

*The reflection problems in the Riccardi-Honders have since been resolved by Astro-Physics through a secondary baffle extension.