The Medusa Nebula is a planetary nebula in the constellation of Gemini. It is also known as Abell 21 and Sharpless 2-274. It was originally discovered in 1955 by University of California, Los Angeles astronomer George O. Abell, who classified it as an old planetary nebula. Until the early 1970s, the nebula was thought to be a supernova remnant. With the computation of expansion velocities and the thermal character of the radio emission, Soviet astronomers in 1971 concluded that it was most likely a planetary nebula. As the nebula is so large, its surface brightness is very low, with surface magnitudes of between +15.99 and +25 reported.

Telescope: ASA N16 f3.6
Mount: Astro Physics 1200GTO
Camera: SBIG STL-11000M
Guider: SBIG STL-Internal

H-alpha: 32×10 mins = 320 mins

Total Imaging Time: 5h 20m

Data Imaged remotely over 5 nights during December 2008.
Data acquisition & Processing by David Churchill.

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