M17 Swan Nebula

Swan Nebula


Swan Nebula This is the result of a sequence taken with

- RNT 24"

- Canon EOS 450d (unmodified)

- 10 pictures of 360 seconds in RGB

- 7 pictures of 480 seconds in OIII

- 25 °C Ambient Temperature

Right Ascension 18:20 (h:m)
Declination -16:11 (deg:m)
Distance 6000 (ly)
Visual Brightness 6.0 (mag)
Apparent Dimension 11 x 11 (arc min) core

This is Omega Nebula, also known as Swan Nebula or Horsehoe Nebula.

It's a charming HII nebula in Sagittarius Constellation.
It was discovered by Philippe Loys de Chéseau in 1734.

We can estimate that the Omega Nebula lies at about 6,000 light-years from Earth and it spans some 18-20 light-years in diameter.
The whole cloud of interstellar matter in which M17 lies is roughly 40-50 light-years in diameter.
The total mass of the Omega Nebula is an estimated 800 solar masses according to SEDS.
 The nebula shines also by excited emission caused by the high-energy radiation of young stars

This picture is made by fusing 2 different data sequences, one in RGB light and one in OIII wavelength, for better showing some chromatic details. OIII light is used only on color channel, not in Luminance channel.

OIII light is overcome by Ha light (also with a unmodded DSLR), but can give some interesting cromathic tone, mixed with the "true color" light sequence.
I didn't used a long exposure time because this nebula is quite bright

Here you can find a comparison between "RGB only version" and "RGB + OIII version"