The Crescent Nebula, NGC 6888 (top right) is an emission nebula in the constellation Cygnus, about 5000 light-years away. Like most of this region around Cygnus, you can't do anything in hydrogen-alpha or sulfur2 without wading through clouds of the stuff—billowing, eddying, and general nebulousing. It's beautiful. There's a Wolf-Rayet star, WR 136, at the lower left edge of the Crescent Nebula (from this angle), and it's stirring up violent stellar winds and blazing quickly through its life; it's expected to go supernova in a couple hundred thousand years, and it's only a four or five million years old. WR stars are unusual: they're very bright--thousands of times brighter than our sun, and they burn much hotter, thousands of times hotter than almost all other stars. And they have very short lifespans. From Wikipedia: "According to recent estimations, WR 136 is 600,000 times brighter than the Sun, 21 times more massive, and 5.1 times larger. Its surface temperature is around 70,000 kelvins". Notes: Astronomik Ha, OIII, and SII filters, William Optics GT81 at f/4.7, ZWO ASI1600MM Pro cooled mono camera, on an iOptron CEM25P mount.
Sharpless 2-101, the Tulip Nebula (top left) is an emission nebula in Cygnus, about 6,000 light-years away. The microquasar Cygnus X-1 is the bright star just above the top point of the Tulip in this image. Cygnus X-1 is famous for being one of the first suspected blackholes, as well as a famous bet between physicists Stephen Hawking and Kip Thorne over that possibility. Hawking conceded to Thorne in 1990 as evidence for a blackhole mounted. Although the Tulip (Sh 2-101) stands out brightly with oxygen in blue, the whole region around the constellation Cygnus is cloudy with interstellar dust and gas. Notes: Astronomik Ha, OIII, and SII filters, William Optics GT81 at f/4.7, ZWO ASI1600MM Pro cooled mono camera, on an iOptron CEM25P mount.
I spent most of last night's imaging run, about 5.5 hours, on this two-panel mosaic of NGC 7000, the North America Nebula and IC 5070, IC 5067 the Pelican Nebula. NGC7000 and this whole area is one of those deep sky objects with which you can do amazing things in narrowband or broadband color, and turns out beautifully in RGB, bi-color Ha and OIII, even Hydrogen-alpha by itself. For this shot I went with the Hubble Palette in SHO, mapping SII-Ha-OIII to RGB, Sulfur = Red, Hydrogen = Green, Oxygen = Blue. This is why you see aqua and gold standing out in many of the Hubble images. It also affects star color, and you end up with some shade of purple.
Here's an update with the two-panel mosaic of the North America Nebula (NGC 7000) and Pelican Nebula (IC 5070, IC 5068). I fixed the stars and toned down the whole image
Here's another one from last night's run, a wide-field view of the Eagle Nebula (M16, NGC6611) in IR-OIII-Ha with Ha luminance. From our perspective Messier 16--Eagle Nebula--sits just north of the Milky Way's dense core of stars, bands of clouds, dust, hydrogen, and other galactic detritus. I wasn't very hopeful with the IR subs, but the Ha subs were beautiful. The OIII frames were about what I expected--not too much but enough to include them. To brighten things up I went back and added the processed Ha stack as a luminance layer. Yes, this may be a spectacularly weird color arrangement, but we're working in false color imaging already, and this doesn't seem that far off from our galaxy's actual core colors--at least in terms of the bands of dust and ionized gases.
Here's the Ha stack:
For comparison (with NGC 6611 above), here's the processed version of the Eagle Nebula (M16) I took last year with a slightly different setup--same William Optics scope + Atik414EX mono CCD camera. This is a bi-color hydrogen-alpha and oxygen3. With this one I think I had my OIII frames mapped to G and B channels, and Ha mapped to the Red channel.
Finally a clear-ish night! I spent almost five hours capturing data, most of it after midnight, when the skies cleared noticeably. And I spent the majority of that time on the Eastern Veil Nebula (Caldwell 33). The big bright area is NGC 6992, and all of this comprises one side (east side) of the Veil Nebula, a supernova remnant from a massive star that ended it all around 8,000 years ago. I will come back on another clear night to get the brighter and larger Western Veil. And this nebula is large, roughly 3 degrees in diameter, covering 36 times the area of a full moon. I shot this in Ha and OIII, 22 x 5 minute exposures for each filter, with the WilliamOptics GT81 and ZWO ASI1600MM-Pro mono camera running at -20C.
Here's the William Optics GT81 and ZWO cameras I'm using for narrowband imaging:
Here's a crop of NGC 6992, 6995, et. al. Eastern Veil Nebula is a supernova remnant in Cygnus, made up of clouds of dust and ionized hydrogen and oxygen.
The dust and hydrogen gas of NGC 2327 "Parrot Nebula" and IC 2177 "Seagull Nebula" span 100 lightyears between the constellations Monoceros and Canis Majoris. This is another one from last night (New Years Day). After shooting the Flaming Star Nebula for several hours, I dropped down to IC 2177 for the remaining clear skies (up to around 1am). Neither of these targets are strong--or have anything showing up--in the oxygen bandpass. I ended up cutting the OIII frames and going with bi-color Ha and SII. Exposures: 28 x 300 seconds of Ha, 26 x 360 seconds of SII. Equipment: William Optics GT81 APO refractor, ZWO ASI1600MM-Pro monochrome 16MP camera (unity gain 139/21), Astronomik filters, iOptron CEM25P mount, INDI/Ekos/KStars running in Stellarmate/Raspberry Pi 3b+
The star at the core of this nebula is the "Flaming Star", AE Aurigae, in the constellation Auriga (The Charioteer), and all the surrounding dust and clouds of hydrogen is called the Flaming Star Nebula (IC 405). This emission nebula is around 1500 lightyears away and it's fairly large, about 5 lightyears across (roughly 47 trillion kilometers or 30 trillion miles across).
What's interesting is that even though AE Auriga is lighting up the nebula, it was not formed there, but rather is a "runaway star" that was probably ejected several million years ago from the star formation furnace in the core of the Orion Nebula. The star is moving quickly through the nebula, producing a violent bow shock with a wave of high energy electromagnetic radiation.
Frames: 23 x 300 seconds of Ha, 5 x 300 seconds of OIII (I was not picking up oxygen at all!), and 20 x 360 seconds of SII. Equipment: William Optics GT81 APO refractor, ZWO ASI1600MM-Pro monochrome camera (unity gain 139/21), Astronomik filters, iOptron CEM25P mount, INDI/Ekos/KStars running in Stellarmate/Raspberry Pi 3b+.
Wide-field of the Wizard Nebula surrounding the open star cluster NGC 7380 in the constellation Cepheus, about 7,200 lightyears aways from us. I reduced the saturation so that you hardly notice the differences in the RGB mix, mostly R and B because this is a bi-color set with Ha and OIII. I think I prefer this reduced color or even a completely desaturated (grayscale) version. There are so many stars in this image and I'm not a fan of the off-color red and blue stars you get with narrowband. Also in this shot, I particular like the dark band at the top left. These "dark fog" or dark nebula regions consist of interstellar gas and dust that absorb the light from surrounding stars, and the constellation Cepheus has some famous dark cloudy areas, B 174, 150, and several around IC 1396. (16 x 300 second exposures in Ha and OIII, Atik 414EX mono CCD, Astronomik 12nm Ha, OIII filters, William Optics ZS61 + WO Flat F6A f/4.7, CEM25P EQ mount, Orion OAG + ZWO ASI120MM-Mini guide cam, Stellarmate OS (INDI/KStars/Ekos) running on Raspberry Pi 3b+).
Here's NGC 281 ("Pacman Nebula") in the Hubble Palette (SII, Ha, OIII -> RGB). NGC 281 is an emission nebula, about 9,200 lightyears away in the constellation Cassiopeia. I re-stacked and reprocessed some hydrogen-alpha, oxygen-3, and sulphur-2 image data I shot several months ago, and I'm happier with this latest result than I was then. It's called the Pacman Nebula because it sort of looks like the classic video game character. (6 x 1200 second exposures in Ha, 5 x 1200 sec OIII & SII with 16 dark frames, Atik 414EX mono CCD, Astronomik 12nm Ha, OIII, SII, William Optics GT81, CEM25P EQ mount, WO 50mm guidescope with ZWO ASI120S-MM guide cam, INDI/KStars/Ekos observatory control).