| Classification: |
Planetary Nebula M57 / NGC6720 |
| Constellation: |
Lyra (LYR) |
| Object Location: |
Ra 18h 54m 07s Dec +33° 03’07° (current) |
| Size & Distance: |
3.0 x 3.0 Apx 2300 light years. |
|
| Date & Location: |
05-2/3-2008 Palomar Mountain, CA. |
| Exposure: |
Ha= 16 @ 15min. RGB= 3 ea. @ 5min, all (bin 2x2) |
| Optics: |
Telescope Engineering Company APO140ED @ f/7 F/L 940mm. |
| Mount: |
Astro-Physics 900 GTO / ATS 10x36 pier. |
| Camera: |
SBIG-ST10XME / Guided by 2045 SBIG-RGH |
| Filters: |
Astrodon 6nm Ha, G2 RGB |
| Software: |
MaxImDL 4.56, Photoshop CS |
|
| Notes: |
Sky conditions: Above average seeing, Light wind, Temp 50°
Image Field of view is 35 x 52 arcmin.
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The Ring Nebula, M57 or NGC 6720 is a planetary nebula in the northern constellation of Lyra. Such objects are formed when a shell of ionized gas is expelled into the surrounding interstellar medium by a red giant star, which was passing through the last stage in its evolution before becoming a white dwarf.
M57 is 2,300 light-years from Earth. It has a visual magnitude of 8.8v and photographic magnitude of 9.7p. Photographs taken over a period of 50 years show the rate of nebula expansion is roughly 1 arcsecond per century, which corresponds to spectroscopic observations as 20–30 km s−1. M57 is illuminated by a central white dwarf.
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