Eagle Nebula
Eagle Nebula
M16 & IC4703
Open Star Cluster and Emission Nebula in Serpens

Click here for other versions: 1580x1053 40%  2568x1711 65%  3951x2633 full res
Click on image to toggle between the version in the colors of the Hubble Palette, a true-color version, and the grayscale (mostly Ha) version


Eagle Nebula: This field contains most of the Eagle Nebula, which consists of an open star cluster (catalogued as M16), and an emission nebula (catalogued as IC4703). At the center of this field are the gas clouds made famous in the Hubble photo entitled "Pillars of Creation." Another piece of this image that has been imaged by Hubble is the almost-horizontal spire to the left of the Pillars of Creation; this feature is 9.5 light years long. To see a little display of the two Hubble photos (the original, iconic one taken in 1995, and the more recent one--in visible light--taken in 2014, and a full resolution crop of mine (with all three shown at the same image scale), click here.

I previously imaged this area as part of a two-panel, wide-field mosaic with my smaller scope (it shows up best in the highest-resolution version; it's really small). This area is in the heart of the larger, bird-shaped nebula at the upper left of that image.

These are part of a large star-forming region, located in the Sagittarius arm of the Milky Way. There are a number of what look like black blobs floating around in the field; astronomers think that these (so-called "Bok globules") are "protostars," and may congeal into stars in time. There is a lot of cold hydrogen gas in this field, showing up in this set of photos as the dark clouds (dark because they don't allow light to pass through them; the stars you see superimposed onto them are between them and us). This region is about 7,000 light years away, and shines at approximately apparent magnitude 8. The cluster is estimated to be 5.5 million years old, and the nebula a bit older.

Technical Information:

Both of the color images are luminance-layered images. LRGBSiiHaOIII : 320:320:240:280:360:900:450. All R, G and B images were unbinned 20-minuted exposures; all Ha, OIII and Sii were unbinned 30-minute exposures. The Luminance layer of the HaRGB image consists of a blending of the master red-filtered image, the master Ha-filtered image, the master OIII image, and the master Luminance- filtered image; the red channel was a blending of the red-filtered image and the Ha-filtered image; the green channel was a blending of the green-filtered image and the Sii-filtered image, while the blue channel is a blending of the blue-filtered image and the OIII-filtered image. The Sii:Ha:OIII (Hubble palette) image was made by using "mapping" the Sii to the Red channel, the Ha to the Green channel, and the Sii to the Blue channel, with the luminance layer consisting of a blending of the Ha-filtered image, the OIII-filtered image and the luminance layer of the HaRGB version.

Equipment: RC Optical Systems 14.5 inch Ritchey–Chrétien carbon fiber truss telescope, with ion-milled optics, SBIG STL11000M with internal color filter wheel (Astrodon Type II filter set), on a Bisque Paramount ME German Equatorial Mount.

Image Acquisition/Camera Control: Maxim DL, controlled with ACP, working in concert with TheSky v6, guided by an SBIG AO-L attached to a MOAG.

Processing: All images calibrated (darks and dawn flats), aligned and combined in Pixinsight. Color combine in Pixinsight. Finish work (curves and levels, adjustment of contrast, and some sharpening of the luminance layer) was done in Photoshop CS5.

Location: Data acquired remotely from Fair Dinkum Skies, Moorook, South Australia.

Date: Images taken on many, many nights from July 2015 through September 2015; conditions were uniformly atrocious, with rain, clouds and fog the norm during that time. Image posted on September 23, 2015.

Copyright 2015 Mark de Regt

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