Abell 21

Planetary Nebula in Gemini

Uploaded 2/27/02

This splendid object in the heart of Gemini is not well known to most observers because of its low surface brightness and the nearby Eskimo Nebula which overshadows it in brightness but not sheer size. While only a dim 11.3 magnitude, this light is spread over 12 arcmins, taking up the entire CCD field. Roughly round in shape, its shape more resembles a supernova remnant rather than a planetary nebula. But the blue dwarf central star seen clearly here, burning at 16th magnitude is the give away, the progenitor of the nebula.

Processing: Dark calibration, and gamma boost in AIP, followed by RL deconvolution, and touch up in Photoshop.

Instrument:  12.5" f/5 Home made Newtonian
Platform:  Astrophysics 1200 QMD
CCD Camera:  SBIG ST7E w/Enhanced Cooling
Exposure:  L(LRGB) = 60:20:20:36 (RGB Binned 2x2)
Filters:  RGB Tricolor
Location:  Payson, Arizona
Elevation:  5150 ft.
Sky:  Seeing FMHW = 2.2 arcsec, Transparency 8/10
Outside Temperature:  0 C
CCD Temperature:  -35 C
Processing:  Maxim DL, Photoshop, AIP4WIN, PW Pro.




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