Orion with Barnard's Loop (combined CCD/Film mosaic)

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Higher resolution (1024x1600) versions: H&alpha (b/w) and color.

The constellation of Orion features one of the largest emission nebulae in the sky: Barnard's loop (discoverd by E. E. Barnard around 1900), which was probably formed by a series of supernova explosions some 3 million years ago. Also visible are Great Orion Nebula (M42, overexposed) and the Horsehead Nebula.

This Hα/color mosaic is a combination of many CCD and film images, recorded over a time span of four years. The Hα frames are the most recent and show McNeil's newly discovered nebula (see this enlargement). 8 fields were photographed from locations in Germany and South Africa and stitched together using techniques developed for assembling my all-sky panorama. The color mosaic was recorded on Kodak PJ-400 negative film at Organ Pipe Cactus National Monument, Arizona. Both the red and luminance channel were replaced with the Hα data. Total exposure time: approx. 8.5 hours.

Lens Hα: Minolta 1.4/50 mm lens, stopped down to f/2.8 or 2.4
Color: Minolta 2.8/135 mm, stopped down to f/4
Camera Starlight Xpress SXV-H9 and Minolta SRT-101
Mount(s) Losmandy G-11 and Super Polaris DX
Filter Astronomik Ha (13 nm FWHM)
Guiding ST-4 autoguider (Hα only)
Date Hα images: 20 Feb. 2004 (Germany) and 23 Mar. 2004 (South Africa)
Color: 31 Dec. 1999, 03 Jan. 2000
Exposure time Ha: each field 2x15 min; color: each field 45 min
Site Hα: Baruth, Brandenburg (Germany) and Ezeljaght Farm near Sutherland (South Africa).
Color: Organ Pipe Cactus National Monument, Arizona.

Processing Bias subtraction, dark frames and digital development: IRAF;
mosaic assembly: SExtractor, Match, custom software and Swarp;
Post-processing: Gimp

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© 1999-2004 Axel Mellinger
Send comments and bug reports to: axm@rz.uni-potsdam.de