Barnard 11-12-13 deep H-alpha

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This is the longest exposure I've ever made for a single image up to now: more than 46 hours of exposure! Most of the exposure is in H-alpha light, and such a long exposure was needed because of the faintness of the nebula associated with the star cloud and dark nebula region. A relatively short RGB exposure was added for natural color composition.
The most prominent features in this field are the dark nebulas. The one near the center and to the left is Barnard 13, while the one near the lower edge is Barnard 12 (alias LDN 1406). The one near the top-right coner is
Barnard 11 (alias LDN 1398). Many other smaller dark nebulas are framed, also partially: Barnard 8, Barnard 21 (LDN 1404), LDN 1395, 1396, 1399, 1400, 1401, 1402, 1403, 1407.

Technical Data
Optics TEC 140
Focal Length
1011 mm
Focal Ratio f/7.2
Exposure Time Total 46 h 40 min, composed of Ha 43 h, RGB 70:60:90 min (single exp of 30 min for Ha, 10 min for RGB)
CCD SBIG STL-11000M @-35°C and -40°C
Location Bogli (PC, Italian Apennines) at 1350 m height - for 6h of Ha and all RGB
Tradate (VA, Po Valley) at 305 m height - for 37 h of Ha
29-30 December 2013 (from Bogli)
2-3-4-5-6-7-8 December 2013 (from Tradate)
Mount Gemini G-41 (from Bogli)
Schmidth fork mount (from Tradate)
Tracking Lodestar on an 80mm f/5 refractor
Temperature and humidity T= -2 to -5 °C, RH=100% (from Bogli)
T= -1 to +3 °C, RH=100% (from Tradate)
Sky brightness at zenith (with SQM-L) 21.1 mag/arcsec^2 (from Bogli)
from 18.8 to 19.6 mag/arcsec^2 (from Tradate)
Notes First trial of mixing home and mountain exposures with this setup.

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