NGC 7129 is a reflection nebula visually located in the constellation Cepheus. The blue color comes from the light from many young blue stars (more than 130 which are only a very few million years old; for reference, our sun is about 5 billion years old) reflecting off the gas/dust of the region. The red crescents are Herbig‐Haro objects. The relatively fine structure of the blue reflection nebula is a result of the stellar winds caused by the energetic young stars pushing back the gas/dust cloud.

In the top right of the photo, you can see the bottom half of a nice open star cluster, NGC 7142 (just above two tiny edge-on spiral galaxies; it is perhaps a symptom of how much gas/dust there is here that there are so few background galaxies).

This nebula is about 3300 light years away from us, and is about fifteen light years across at its widest point. The entire field of the uncropped image is about the same width as a full moon.

Technical Information:

(HaL)(HaR)GB: 420:525:225:180:380 (a total of almost 29 hours of exposures); luminance layer consists of blend of 35 fifteen-minute images using a luminance filter and 14 thirty-minute images using an Ha filter; R channel is a blend of the Ha data and 15 fifteen-minute images taken through a red filter; G consists of 12 fifteen-minute images taken through a green filter, while B is the combination of 19 twenty-minute images taken through a blue filter.

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 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, and combined in Pixinsight. Color combine in Pixinsight. Some finish work (NoiseXTerminator, background neutralization, BlurXTerminator, color calibration, gradient removal, HDR Multiscale Transform) done in Pixinsight; some finish work (Neat Image noise reduction, LRGB combination, high pass filter, contrast and saturation adjustment) was done in Photoshop CC.

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

Date: Images taken on many nights in July and August of 2020. Image posted September 4, 2020.

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

Seeing: Generally pretty good, with calibrated luminance images varying from 1.6 to 2.3 arcsecond FWHM

CCD Chip temperature: -25C

Copyright 2020 Mark de Regt

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