NGC6946: This is a very dim, 10th magnitude galaxy in Cepheus toward Cygnus, approximately ten million light years from Earth. Looking from the bright core outward along the spiral arms, the galaxy's colors show a change from the yellowish light of old stars in the galaxy's center to young blue star clusters and reddish star forming regions. NGC 6946 is also bright in infrared light and rich in gas and dust, exhibiting a high star birth and death rate. During the 20th century, at least six supernovae, the death explosions of massive stars, were discovered in NGC 6946. A small barred structure is just visible at the galaxy's core.

Technical Information:

LRGB: 165:50:50:50 (Luminance layer consists of 11 fifteen minute images, unbinned; R, G and B consist of 5 ten-minute images, all binned 2x2).

Equipment: 12" RCX400 at f/8.5, and an SBIG ST-8XE camera/CFW-8 color filter wheel, guided with an SBIG AO-7, guiding at 5 Hz for the luminance images, and 3Hz for color channels.

Image Acquisition/Camera Control: CCDSoft V5.

Processing: All images calibrated (darks and dawn flats) and registered in CCDSoft. Luminance layer average combined in Ray Gralak's Sigma Beta; color channels average combined in CCDSoft. One fast and fifteen slow (high frequency components only) iterations of Richardson-Lucy applied in AIP4WIN. Color combine, many careful adjustment of curves and levels, and selective Gaussian blurs and unsharp mask in Photoshop; repair of bloomed stars performed in CCDSoft using Ron Wodaski's bloom removal software.

Location: My yard in Redmond, Washington, elevation 500'.

Date: Luminance images taken during the nights of 7/1/06 and 7/2/06; RGB images taken during the night of 7/1/06.

CCD Temperature: -20C

Seeing: 2.0 arcsecond FWHM on typical calibrated image.

Transparency: Poor

Moon Phase: No moon during imaging

Copyright 2006 Mark de Regt