This is my biggest project to date.
A 4-panel mosaic encompassing the area from the Horsehead/Flame nebulae to the Great Orion Nebula. I dedicated every available astrophotography night this winter to capture this image (8 nights in total).

There were a couple of challenges capturing and processing this image:

1. I had to decide on the right combination of exposures to be able to resolve that M42 core while extruding as mush detail as possible everywhere else. I ended up stacking 2 sets of data and used the HDRCompoistion tool in Pixinsight to get the best of both worlds. After stretching the data making sure to protect the core as much as possible with masking, I used a combination of stacks of 10s, 5s, and 1s exposures to mask in additional detail in the core using Photoshop. I prefer to show how bright M42's core is and was extra careful no to over do it. My goal was to make sure the trapezium is barely visible. I feel this is a more accurate representation.

2. My Plan was to shoot in broadband without a filter, then collect some Ha data using the Antlia ALP-T Dualband filter, extract that Ha and combine it with the broadband data to create the HaRGB image. Halfway through the project I purchased the Antlia Quad Band filter, and of course I wanted to try it right away. I thought I can just assume the Broadband and Quad band can be stacked interchangeably, but when it came time to stack, Astro Pixel Process did not agree. I did not consider the fact that equal exposure times and ISO with and without the filter will yield different star brightness and intensities. The result was extreme artificates around the stars. Luckly, I managed to find the right combination of exposures to stack together without artificates, then after removing the stars, used HDRcomposition to blend both sets of stacks as explained above.
The winning combinations were the following:
- 300s/ISO1600 Quad Band + 300s/ISO1600 No Filter + 180s/ISO800 No Filter
- 180s/ISO800 Quad Band + 60s/ISO800 No Filter

I am very impressed with how the Antlia filters performed with regards to halos, especially the Dual ALP-T. Al Nitak hardly shows much halos, although I had to do some light cosmetic surgery to subdue the halo around Al Nilam.

I'm glad I did not shy a way from this project, many new things to learn and many hours of hair pulling (AKA astrophotograpyh fun). Hope I have the courage to collect more data to add to this one in the future.

Clear Skies