Emission Nebula in Cygnus

Click here for higher-resolution, uncropped versions:  40% (1620x1618)  65% (2633x2630) 100% (4051x4046)
Click on image to toggle between pure Ha grayscale version and color version


Sh2-106 is a small emission nebula and star-forming region. It was long thought to be a planetary nebula, because of its bi-polar appearance, but it is an emission nebula, formed by the hot gasses being emitted at both poles by a huge (15 times the mass of our sun), new star at its center. The characteristic red color is a result of the hydrogen being ionized (stripped of its electron) by the progenitor star.

Sh2-106 is thought to be about 2,000 light years from Earth, and has an apparent length of about 3 arcminutes (quite small), giving it an actual length of about 2 light years.

If you look at the uncrooped version, you will see lots of faint nebulosity/dust in the image.


Technical Information:

Ha:OIII:L:R:G:B: 570:660:375:105:180:240 (a total of over 35 hours of light-frame exposure time); luminance, red and green exposures were all 15-minute exposures; blue all 20-minute exposures; Ha and OIII were all 30-minute exposures. The luminance layer consisted of a blend of: (i) 25 fifteen-minute images through the luminance filter, and (ii) 19 Thirty-minute images through the Ha filter. The red channel is a blend of the red-filtered data and the Ha-filtered data; the green channel is a blend of the green-filtered data and the OIII-filtered data, and the blue channel is a blend of the blue-filtered data and the OIII data. The OIII emissions were markedly weaker than the Ha emissions, so only applied very small influence on the image (primarily changing the hue of the brightest part of the nebula itself).

Equipment: RC Optical Systems 14.5 inch Ritchey-Chretien carbon fiber truss telescope, with ion-milled optics and RCOS field flattener, at about f/9, and an SBIG STX-16803 camera with internal filter wheel (SBIG filter set), guided by an SBIG AO-X, all riding on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP Expert/Scheduler, working in concert with TheSky X.

Processing: All images calibrated (darks, bias and sky flats), aligned, combined and cropped in Pixinsight. Color combine in Pixinsight. Some finish work (background neutralization, color calibration, NB blend, deconvolution, multiscale linear transform, HDR multiscale transform, and noise reduction) done in Pixinsight; some cleanup finish work was done in Photoshop CC.

Location: Data acquired remotely from Sierra Remote Observatories, Auberry, California, USA.

Date: Images taken on many nights in April, May and June of 2022. Image posted July 24, 2022.

Date: Image scale of full-resolution image: 0.56 arcseconds per pixel.

Seeing: Generally good; luminance images varied in FWHM from 1.7 to 2.5 arcseconds.

CCD Chip temperature: -25C

Copyright 2022 Mark de Regt

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