Veil Nebula (APOD, Nov 26th 2012)

Veil nebula, supernova remnant in Cygnus. Image shown at 50% of size.  Clic at the bottom of this image for a 100% size image. Astronomy Picture of the day, November 26th 2012.
Equipment: Takahashi FSQ106 scope. ASA DDM85 mount. SBIG STL11000 camera. Color data obtained with Baader filters (Red, Green and Blue) and luminance data with Astronomik CLS-CCD filter (a light pollution rejection filter)
Location: Pozuelo de Alarcon (10 Km away from Madrid), Spain. Date: Summer 2012. Exposure: 5 minutes unguided subexposures totalling 33.3 hours (150x5m CLS, 86x5m Red, 78x5m Green, 86x5m Blue)
Processing: PixInsight and Photoshop

Image planning and processing: Because of our high light pollution from nearby Madrid (zenit sky brightness of 18,0 to 18,5 magnitudes/square arcsecond on moonless nights), unguided subexposures were limited to 5 minutes each and luminance was obtained through a light pollution rejection filter (CLS-CCD). A total exposure over 33 hours was necessary to obtain an adequate signal to noise ratio in the sky backgroung. To eliminate the sky gradients in the image, a PixInsight tool called Dynamic Background Extraction was very useful.