Wednesday, January 12, 2011
Abell 21, Sh2-274, the "Medusa Nebula", project continues
Colors and image are in "preview" mode at the moment, I will shoot more data, when weather allows to finalize this image.
The Medusa Nebula in Gemini is also known as Abell 21 and Sharpless 274. It's a large nebula as a planetary one, due that the surface brightness is very low, between 15.99 to 25.
At highest elevation in South, it was about 35 degrees and when I started the altitude was only a 25 degrees.
I started this project back in March 14. 2010 with few frames of H-alpha. I was able to continue the project last night.
Previous version can be seen here:
http://astroanarchy.blogspot.com/2010/03/abell-21-sh2-274-medusa-nebula-start-of.html
After a long cloudy period, we had a clear night, with relatively good seeing. Transparency was very poor and the light pollution was massive due the local sport centers lights. This target is never very high, up here at 65N and a Local paper mill sent massive amounts of "smoke" over the object. At the end I was able to capture only 5 frames of H-a and three frames of S-II, before I had to close down.
There was only one O-III frame from last session,
Natural color composition from the emission of ionized elements, R=80%Hydrogen+20%Sulfur, G=100%Oxygen and B=85%Oxygen+15%Hydrogen to compensate otherwise missing H-beta emission. This composition is very close to a visual spectrum.
Previous version can be seen here:
http://astroanarchy.blogspot.com/2010/03/abell-21-sh2-274-medusa-nebula-start-of.html
After a long cloudy period, we had a clear night, with relatively good seeing. Transparency was very poor and the light pollution was massive due the local sport centers lights. This target is never very high, up here at 65N and a Local paper mill sent massive amounts of "smoke" over the object. At the end I was able to capture only 5 frames of H-a and three frames of S-II, before I had to close down.
There was only one O-III frame from last session,
Technical details:
Processing work flow:
Image acquisition, MaxiDL v5.07.
Stacked and calibrated in CCDStack.
Levels, curves and color combine in PS CS3.
Telescope, Meade LX200 GPS 12" @ f5
Camera, QHY9 Guiding, SXV-AO @ 4,5Hz
Image Scale, 0,75 arcseconds/pixel
Baader H-alpha 7nm 5x1200s, binned 2x2 +
Baader H-alpha 7nm 7x1200s, binned 1x1 from previous session at March 14.2010.
Baader O-III 8,5nm 1x1200s, binned 4x4
Baader S-II 8nm 3x1200s, binned 4x4
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