Composite astrophotograph

Copyright Anglo-Australian Observatory/Royal Observatory, Edinburgh.
Photograph from UK Schmidt plates by David Malin, Sydney, Australia.

The Orion nebula is the nearest major star-forming region at a distance of roughly 1,500 light years. It is composed of dust, gas, and bright stars - many of which are recent formations within the nebula. The picture is about 58-arc minutes wide, corresponding to approximately 25 light years at the distance of the nebula. The UK Schmidt Telescope (equivalent to a 3.05 m focal length, f/2.5 reflecting objective), was used to sequentially expose three hypersensitized monochrome photographic plates with separate filters that recorded red, green, and blue light. Each monochrome image was subject to photographic unsharp-masking to extract detail in high densities. The images were then recombined on color negative film to produce a true-color image.