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About this Image
The faint Medusa Nebula in Gemini, designated as Abell 21 or PK 205+14.1 is a very ancient planetary nebula in the constellation of Gemini.
The inner bubble shows some hints of blueish structure, indicating that the central star (the blue one in the center) is still hot and makes the gas flouresce.
410mm cassegrain in corrected prime focus at f/3
|Camera||SBIG STL-11000M at -30C, internal filter wheel|
|Filters||Astronomik H-alpha (15 nm), green, blue|
|Date||Mar 06, 2006.|
|Sky Conditions||mag 5 sky, Moon up, temperature -3 C,|
|Exposure||Ha:G:B = 120:40:60 minutes (30-minute sub-exposures Ha, 10 min for G, B), all 1x1.|
|Processing||Image aquisition, calibration and color combine in Maxim DL 4.11; curves, color balancing, light unsharp mask in Photoshop; Noise reduction by Neatimage|