Emission Nebula in Cepheus
NGC7538: This is a faint emission nebula in Cepheus, quite near the Bubble Nebula, of which I also have an image. The gas forming the nebula is ionized by the bright, hot stars toward the center of the nebula. Associated with this visible part is a portion unseen visually, but which is an area of active star formation (in June 2001, a "protostar" with 300 times the mass of our Sun was discovered). Further studies of the object, named NGC 7538S, may yield important clues about the formation process of very high-mass stars. NGC7538 is about 7000 light years from Earth.
RRGB: 144 (18x8 min):80 (10x8 min):80 (10x8 min):130 (10x13 min) (all unbinned).
Equipment: 10" LX200 at f/4.6, and an SBIG ST-7E camera/CFW-8 color filter wheel
Image Acquisition/Camera Control: CCDSoft V5.
Processing: All images calibrated (darks and dawn flats) and registered in AIP4WIN. Luminance images average combined in Ray Gralak's Sigma Reject program; RGB median combined in CCDSoft. 5 iterations of Richardson-Lucy (high frequency only) applied to luminance layer in AIP4WIN. Color combine, and adjustment of curves and levels, performed in Photoshop 6.
Location: My back yard in Bellevue, Washington, elevation 600'.
Date: All images taken during the night of 9/13/01.
CCD Temperature: -15C
Copyright Mark de Regt, 2001