Russell Croman Astrophotography  



The Great Orion Nebula
in Elemental Colors

About This Photograph

The Great Orion Nebula is a vast region of intense star formation. Massive, hot young stars, destined to lead short lives due to the rate at which they are consuming their hydrogen fuel, are the illuminating sources for the clouds of gas and dust that we see. Their intense ultraviolet light excites atoms in the nebula, causing them to fluoresce: each chemical element re-emits light in its own specific colors.

In this image, special filters were used to isolate the light from three of these elements, and these exposures were then combined to form a color composite: red for sulphur, green for hydrogen, and blue for oxygen. In reality, both sulphur and hydrogen emit a deep red color, while oxygen emits a teal hue. The "mapped" color assignment in this image highlights the distribution of energized atoms in the nebula.


Technical Details

Optics:14" f/10 RCOS Ritchey-Chr├ętien Cassegrain
Mount:Astro-Physics AP1200GTO
Filters:Custom Scientific 5nm S-II, H-alpha, O-III
Dates/Times:19, 27 January 2004
Location:my backyard observatory in Austin, Texas
Exposure Details:S-II: 2 hours.H-alpha: 3.5 hours.O-III: 2 hours
Processing:To generate the color, the three emission-line images were first histogram-normalized, so that they each covered the same total range of brightness. These were then combined into an RGB image, and finally the H-alpha data was used for the luminance (brightness data).


Publication Data for this Photograph

Date Publication Type
2004-08-00 Wiedza i Zycie,
pp. 54-55
2004-07-00 Star Observer,
p. 102
2004-06-13 Austin American Statesman,
pp. K-1, K-3
2004-03-25 Portal do Astronomo,
Image of the Day
Web Site
2004-03-25 NASA's Astronomy Picture of the Day Web Site
Image of the Day
Web Site
2006-11-00 The NewAstro Zone System for Astro Imaging,
p. 199
2007-00-00 Sky & Telescope's Celestial Wonders Calendar 2007,