The Orion Nebula - M 42

The Great Orion Nebula is probably one of the best-known deep sky objects - it’s an easy naked-eye object situated in the sword of Orion, the hunter. For me, this was one of the few deep sky objects I could easily view when I was a kid. Equipped with my Grandpa’s Tasco 60 mm, f14 scope on a spindly alt-az tripod under light-polluted skies, it was one of the few objects I could easily find, focusing in quickly on the Trapezium cluster at the bright heart of the nebula before it moved rapidly out of the field of view. The full extent of the surrounding nebulosity was not part of that narrow view.

Being able to resolve in an eyepiece the stars that form the Trapezium is something of a test of how good the ‘seeing’ is for particular sky conditions, and on that basis I had never really considered imaging this area having seen it all before many times. It’s also one of the first things one might image when getting into AP. However, the fact that this nebula is so bright also makes it incredibly challenging to image well - there is so much dynamic range in this region that the stars of the Trapezium can saturate camera pixels in a few seconds or less, at which point the much fainter surrounding nebulosity remains well below detection limits.

For this image, the aim was to try to capture the Trapezium region, in addition to as much of the surrounding nebulosity possible. I made a series of exposures of different lengths (0.25s, 1s, 10s, 30s and 300s) through RGB filters, and extended out to 600s for hydrogen-alpha - the total exposure time being ~12hrs. The resulting large collection of files was then pulled together and processed using HDR composition within Pixinsight in order to produce a single, huge 64-bit RGB working image. This image was then carefully stretched using the HDR Multiscale Transform tool in combination with the Generalised Hyperbolic Stretch tool (both in Pix).

The resulting wide-field, deep image shows M42, the Orion Nebula in the context of its surrounding faint and dark nebulosity, also including the Running Man Nebula (NGC 1977) - a HII emission and reflection nebula below it.