The Ring Nebula (Messier 57 or NGC 6720) is a planetary nebula in the northern constellation of Lyra. Formed when a shell of ionized gas is expelled into the surrounding interstellar medium by its red giant star, which was passing through the last stage in its evolution before becoming a white dwarf.

This nebula was discovered by the French astronomer Antoine Darquier de Pellepoix in January 1779, who reported that it was "...as large as Jupiter and resembles a planet which is fading." Later the same month, astronomer Charles Messier independently found the same nebula while searching for comets.



In 1800, German Count Friedrich von Hahn announced that he had discovered the faint central star at the heart of the nebula a few years earlier. He also noted that the interior of the ring had undergone changes. The nebula was first photographed by the Hungarian astronomer Eugene von Gothard in 1886.

M57 is 2,300 light-years from Earth. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1 arcsecond per century ( 20–30 km/s). M57 is illuminated by a central white dwarf , whose mass is approximately 1.2 in solar masses.



All the interior parts of this nebula have a blue-green tinge that is caused by the doubly ionized oxygen emission lines at 495.7 and 500.7 nm. In the outer region of the ring, part of the reddish hue is caused by hydrogen emission at 656.3 nm.

About two M57 diameters away, at 2 o'clock is IC 1296, the tiny barred spiral galaxy. It has low surface brightness because IC 1296 is much farther away (about 221 million lightyears) than M57's mere 2300 LY. (Source Wikipedia)

SUPERNOVA ALERT: IC1296 received a visitor sometime around August 11th of this year. If you look closely at the lower spiral arm, you can see a small but bright star. This is supernova 2013ev.

The image was captured with the Meade 12"LX200, using the Atik 383L+ mono at F6.56. Astronomik's 12nm Halpha, OIII and SII narrow band filters were used. All subs were taken at 1x1 bin, -10C, and 10 minutes each.

Ha : 63 subs (10.50 hr) on Sep 14th, 21st, 24th and 25th.

O3 : 19 subs (3.17hr) on Sep 22nd.

S2 : 20 subs (3.33 hr) on Sep 23rd.

Processing was done with PixInsight, following (for the most part) kayronjm's tutorial of Feb. 24th. Only Ha was used to develop the Luminance image. I tried several color mixes before settling on the below formula.

R = 0.50 O3 + 0.50 Ha

G = 0.15 O3 + 0.85 S2

B = S2

North is up (and west is to the right). This is a medium crop, mainly to increase subject size .