I've avoided this target up to now due to its being relatively dim compared to other emission nebula.  However, after transitioning from OSC to monochrome imaging, I felt that with Ha/Sii/Oiii filters that I could give this a decent attempt.  This is, as I assumed, a dim nebula and it was necessary to push it quite a bit to brighten the image/make the nebula stand out.  This can result in a lot of grain in the image which even NXT can't fully correct and also creates other artifacts.  So there is a limit as to how far the image can be pushed, although more data/longer integration time can further mitigate that issue.  At approximately 10 hrs. of integration time, there is no doubt IMO that adding more data as weather permits will enhance this quite a bit.

To complicate my composition a bit, I also wanted to include Mu Cephei - The Garnet Star in the image.  Mu Cephei has quite a bit more history behind and it was even the progenitor of a no longer used class of variable stars.  There is more detail on both the Elephant Trunk Nebula and Mu Cephei below.

The Elephant Trunk Nebula is located in the lower center of the image while the Garnet Star is located in the upper right edge of the image.

After posting the original I discovered I had left off a key step in my post processing.  I had created an Ha mask to bring back/enhance the Ha detail that is sometimes diffused during the processing of the combined palette/RGB image.  I use the LRGB channel combination to to add the Ha as a Lum channel in to the final SHO version (sometimes I use the Ha as a mask first, depending on how the final image looks).  I had also noted that some of the saturation of the stars was lost in the final jpeg image, so I tweaked the saturation in PixInsight to compensate.

Please enjoy, and let me know what you think!!!

CS
Clayton

IC 1396 The Elephant Trunk Nebula
The Elephant's Trunk Nebula is a concentration of interstellar gas and dust within the much larger ionized gas region IC 1396 located in the constellation Cepheus about 2,400 light years away from Earth. The piece of the nebula shown here is the dark, dense globule IC 1396A; it is commonly called the Elephant's Trunk nebula because of its appearance at visible light wavelengths, where there is a dark patch with a bright, sinuous rim.

The bright rim is the surface of the dense cloud that is being illuminated and ionized by a very bright, massive star (HD 206267) that is just to the east of IC 1396A. (In the Spitzer Space Telescope view shown, the massive star is just to the left of the edge of the image.) The entire IC 1396 region is ionized by the massive star, except for dense globules that can protect themselves from the star's harsh ultraviolet rays.

The Elephant's Trunk Nebula is now thought to be a site of star formation, containing several very young (less than 100,000 yr) stars that were discovered in infrared images in 2003. Two older (but still young, a couple of million years, by the standards of stars, which live for billions of years) stars are present in a small, circular cavity in the head of the globule. Winds from these young stars may have emptied the cavity.  The combined action of the light from the massive star ionizing and compressing the rim of the cloud, and the wind from the young stars shifting gas from the center outward lead to very high compression in the Elephant's Trunk Nebula. This pressure has triggered the current generation of protostars.

Mu Cephei The Garnet Star
Mu Cephei (Latinized from μ Cephei, abbreviated Mu Cep or μ Cep), also known as Herschel's Garnet Star, Erakis, or HD 206936, is a red supergiant or hypergiant star in the constellationCepheus. It appears garnet red and is located at the edge of the IC 1396 nebula. Since 1943, the spectrum of this star has served as a spectral standard by which other stars are classified.Mu Cephei is visually nearly 100,000 times brighter than the Sun, with an absolute visual magnitude of −7.6. It is also one of the largest known stars with a radius around or over 1,000 times that of the sun (R☉), and were it placed in the Sun's position it would engulf the orbit of Mars and Jupiter.

The deep red color of Mu Cephei was noted by William Herschel, who described it as "a very fine deep garnet colour, such as the periodical starο Ceti". It is thus commonly known as Herschel's "Garnet Star".   Mu Cephei was called Garnet sidus by Giuseppe Piazzi in his catalogue. An alternative name, Erakis, used in Antonín Bečvář's star catalogue, is probably due to confusion with Mu Draconis, which was previously called al-Rāqis[arˈraːqis] in Arabic.

In 1848, English astronomer John Russell Hind discovered that Mu Cephei was variable. This variability was quickly confirmed by German astronomer Friedrich Wilhelm Argelander. Almost continual records of the star's variability have been maintained since 1881.

Mu Cephei is surrounded by a shell extending out to a distance at least equal to 0.33 times the star's radius with a temperature of 2,055±25 K. This outer shell appears to contain molecular gases such as CO, H2O, and SiO.  Infrared observations suggest the presence of a wide ring of dust and water with an inner radius about twice that of the star itself, extending to about four times the radius of the star.  The star is surrounded by a spherical shell of ejected material that extends outward to an angular distance of 6″ with an expansion velocity of 10 km s−1. This indicates an age of about 2,000–3,000 years for the shell. Closer to the star, this material shows a pronounced asymmetry, which may be shaped as a torus.

Mu Cephei is nearing death. It has begun to fusehelium into carbon, whereas a main sequence star fuses hydrogen into helium. When a supergiant star has converted elements in its core to iron, the core collapses to produce a supernova and the star is destroyed, leaving behind a vast gaseous cloud and a small, dense remnant. For a star as massive as Mu Cephei the remnant is likely to be a black hole. The most massive red supergiants will evolve back to blue supergiants, Luminous blue variables, or Wolf-Rayet stars before their cores collapse, and Mu Cephei appears to be massive enough for this to happen. A post-red supergiant will produce a type IIn or type II-b supernova, while a Wolf Rayet star will produce a type Ib or Ic supernova.