Horsehead NGC7538 Horsehead

(Click on image for Full Resolution)

(Click here for the H-Alpha exposure used in the HaRGB composite)

Date: October 16, 2003
Exposure: HaRGB : 14400:3600:3600:4500
12 x 1200s Ha, 4 X 900s R,G & 5 x 900s B
Processing: CCDSoftV5 for image acquisition, MaxIm for RGB combine, image calibration: 20 flats each Ha,R,G,B, dark subtracted and median combined, 30 bias frames median combined, 16-1800s darks median combined, alignment, normalization, and color combining. Photoshop for Ha+R combine, MaxIm for HaR+G+B combining,Photoshop for final balance and web conversion. The light pollution is always bad on the green set, but I may have discovered a processing sequence that gets most of it out for my conditions. Time will tell. The RGB exposures were done with the humidity pegged on 100%.
Conditions: Above average, Mag 4-4.5 Skies, very clear, but the usual 100% humidity after midnight.
Scope: AP 155 EDF @ F/7 on a Paramount ME
Camera: SBIG ST-8XE/CFW-8A, -20°, Custom Scientific 3nm Ha Filter
Comments: This was taken over 2 nights to get the 4 hours of Ha data needed to have good S/N. The RGB images were taken on the same night. Located in the constellation Cepheus, this nebula is very dim and only approx 10' in size. It is approx. 7000 light year away.