M57-20080702-LRGB Back to Index Page Previous Image Next Image
Imaging Date: 1/2 July 2008

Designation :
M 57, NGC 6720, PN G063.1+13.9, PK 063-13.1, ARO 9

Object Type :
Planetary Nebula

Description :
M57 was the second planetary nebula to be discovered (in January 1779), 15 years after the first one, M27. Antoine Darquier de Pellepoix (Darquier), who discovered the Ring Nebula only a few days before Charles Messier found and cataloged it, described it as "a dull nebula, but perfectly outlined; as large as Jupiter and looks like a fading planet." This comparison to a planet may have influenced William Herschel, who found the objects of this type resembling the planet newly discovered by him, Uranus, and introduced the name "Planetary Nebulae". Herschel described M57 as "a perforated nebula, or ring of stars;" this was the first mention of the ring shape. Oddly, the inventor of the name "Planetary Nebula" did not count this most prominent representative in this object class, but described it as a "curiosity of the heavens", a peculiar object. Herschel also identified some of the superimposed stars, and correctly assumed that "none [of them] seems to belong to it."

Coordinates (J2000) :
RA: 18h53m35.1s Dec: +3301'45"

Constellation : Lyra

Integrated Magnitude : 9.40

Size : 1.4 arcmin

Equipment details :
ART11002 through 10" LX200R, autoguided

Exposure details :
L = 18 x 240s unbinned
RGB = 18 x 120s binned 2x2 each

Seeing was unusually good for these two night of imaging, which combined with the recently tweaked collimation of the scope resulted in a stellar FWHM of ~2.1 arcsec. Some light deconvolution resulted in the stars FWHM of 1.8 arcsec.
I was pleased to be able to clearly distinguish the fourth dim star in the ring, just on the inside edge of the ring, which has eluded me to date.
The collimation still needs refining further - hopefully when I replace the focuser I will be able to fix the residual ccd tilt as well.