Horsehead nebula and neighborhood

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This is the famous field around the Horsehead nebula, a very popular object between the wide public, mainly due to the similarity to the name.
This image shows many objects and colours:

Technical Data
Optics Newton 200 mm (homemade by L. Comolli, F. Riccio and P. Battaglia)
Focal Lenght 1260 mm
Focal Ratio f/6
Corrector Baader MPCC
Exposure Time 2h10m (single exp of 10 min)
CCD Canon EOS 5D with baader filter
Sensitivity 800 ISO
Location Capanne di Cosola (AL, Italian Appennines) at 1500 m height
4 February 2011
Mount Gemini G-41
Tracking Lodestar on an 80mm f/5 refractor
Temperature and humidity T= +2°C, RH=36%
Sky brightness at zenith (with SQM-L) 21.0-21.3 mag/arcsec^2
Notes Great transparency, but very bad seeing, so the stars are not pinpoints.
North at left.
A small amount of H-alpha data was added on the red background, using data from an older image with the Schmidt camera.
Thanks to Daniele Cipollina for some hints about processing.
Diffraction spikes are multiple due to non perfect straightness of the secondary mirror supports.

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