Messier 17
According to Wikipedia:
Catalogued as Messier 17 or M17, the Omega Nebula (also known as the Swan Nebula, Checkmark Nebula, Lobster Nebula, and the Horseshoe Nebula) is an H II region in the constellation Sagittarius. It was discovered by Philippe Loys de Chéseaux in 1745. Charles Messier catalogued it in 1764
M17 lies between 5,000 and 6,000 light-years from Earth and it spans some 15 light-years in diameter. The cloud of interstellar matter of which this nebula is a part is roughly 40 light-years in diameter and has a mass of 30,000 solar masses. The total mass of M17 is an estimated 800 solar masses.
It is considered one of the brightest and most massive star-forming regions of our galaxy. Its local geometry is similar to the Orion Nebula except that it is viewed edge-on rather than face-on.
The open cluster NGC 6618 lies embedded in the nebulosity and causes the gases of the nebula to shine due to radiation from these hot, young stars; however, the actual number of stars in the nebula is much higher - up to 800, 100 of spectral type earlier than B9, and 9 of spectral type O, plus over a thousand stars in formation on its outer regions. It is also one of the youngest clusters known, with an age of just 1 million years.
After my dew heater controller decided to self-combust, I’ve been a bit down about doing astro and gave up several clear nights because the ‘scope would have been covered in dew and I’d end up not achieving anything.
I do (finally) have most of the components to assemble a new (and better) dew heater controller that will be able to drive 2 dew heaters. Sure, it’s nothing high-tech, but it’ll do the job for me.
Anyway, we had a warmer and clear night roll around and I was finally able to scratch another nebula off my ‘must image’ list. All up, I captured 4 hours of data on this one. If I didn’t have to go to work the next morning, I would have been up much later - at least until M17 got too low in the sky to get good data.
Processing-wise, there’s nothing to say here - the usual “stack in Siril, basic pre-proc then into Starnet++ and Affinity Photo”.
I’m impressed with the subtle detail in the outer regions of the nebula, and the billowing, cloud-like patterns in the gas & dust clouds. I keep thinking of upgrading my telescope, but the little SW72 just keeps on giving me great results…
Image data:
- Gain: 100
- Offset: 10
- Temperature: 0 degrees C
- Exposure: 120 seconds
- Frames: 120 Lights, 25 Darks, 50 Flats and DarkFlats (4 hours integration in total)
- Filter: L-Enhance (Ha + Oiii dual-narrowband)
Equipment: SW72ED@420mm / HEQ5-Pro / ASI183MC-Pro / SV165+SV305 / Kstars/Ekos