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M 42 , The Great nebula In Orion
This is a composite of an H-alpha image (2004-04-08), used as a luminosity layer, plus the much earlier RGB image shown below it. The H-alpha image is composed of 60 minutes (12 x 5 minute exposures) through the A-P refractor described below.
Below is the RGB-only layer:
This CCD image of the Great Orion Nebula is a great improvement on my first film version, and a higher resolution image than my 2000 film attempt, seen HERE. However, it still lacks the high resolution needed to resolve the Trapezium stars and the fine detail in the core. It was made as an exercise in layer masking, because the very high brightness of the Trapezium area can not be imaged with the same exposures needed for the fainter outer portions of the nebula. In addition, I'm not satisfied with the range of reds (largely H-alpha light). Undoubtedly, more images of M42 will accumulate in my files until I reach the goal, but this will do for the time being. The bluish tint of NGC 1977, the Running Man Nebula, is just hinted at at the right edge of this image and can be seen in full HERE. (North is toward the right in this image.)
| Date | 2003-01-05, 2003-01-16 |
| Scope |
Astro-Physics 130 EDFs refractor at f/4.5 with ST-10XME CCD camera at -15 °C on the A-P 1200 GTO mount. Guided with an ST-4 on an A-P guidescope. |
| Exposure |
5 x 5 sec and 5 x 1 min each with 1x1 binning with regular R, G, and B SBIG filters for the Trapezium area. 6 x 5 min R, G, and 10 x 5 min B for the outer portions of the image. In addition, 10 x 5 min H-alpha images were obtained on 2003-01-17. SBIG CFW-8 filter wheel. Total exposure times: 35'25" R, G; 55'25" B, 50' Ha. |
| Processing |
Raw frames calibrated and then debloomed with Wodaski's Debloomer plug-in. Each exposure group was stacked and RGB combined in MaxIm 3.09 with R=1.25, G=1.0, B=1.65 weighting. After stretching with levels and curves in PhotoShop 7.0, the three exposure groups were aligned with RegiStar and then layer to provide 5x5 sec for the Trapezium, 5x1 min for the immediately surrounding area, and 6-10x5 minutes for the remainder of the image. Layer masking was carried out as described by Jerry Lodriguss in the January 2001 Sky & Telescope. Noise reduction using SGBNR. Finally, the H-alpha image was added as a luminosity layer in Photoshop. |