Nightscapes & Deep Sky Colors

Astrophotography Brian A. Morganti

Abell 21

Medusa Nebula




The Medusa is an ancient planetary nebula representing a dying star that has shed its outer layers, similar to that of the Dumbbell Nebula and Helix Nebula---but is more distant.  It lies between 1,000 and 1,500 light-years away in Gemini.  The shell of hydrogen gas, glowing red, is energized by ultraviolet radiation from the ember of the fading central star, appearing as a faint blue star in the center of the nebula on this image.  The nebula's name is derived from its delicate filaments.  The Medusa Nebula is so faint that it was not even discovered until 1955 by the Yerkes-McDonald survey (named YM 29) and later designated as Abell 21. 


  • Date & Location:  January 13, 2010  - Bernville, PA

  • Weather:  Calm, 21F.

  • Sky Conditions:  Clear with average transparency. 

  • Optics:  TeleVue NP101is Refractor with 0.8x TeleVue Reducer = 432mm @ f4.3

  • Filter:  Astronomic  EOS clip-in CLS-CCD (Light Pollution Suppression)

  • Mount:  Losmandy G-11 equatorial with Gemini V4

  • Guiding:  Orion Solitaire w/TeleVue TV60is

  • Camera:  Canon T1i (500D) Hap Griffin Modified - Baader UV/IR

  • Exposure:  57 min (1 x 5 min, 1 x 6min, 6 x 8min) @ ISO 800 RAW

  • Calibration Frames:  No dark frame subtraction (21F)

  • Processing:  Photoshop CS4, Noise Ninja, NIK, Noel Carboni Astronomy Tools

  • Comments:  Overall pleased with this image considering that like most Planetary Nebula the medusa is quite small and was heavily cropped in order to enlarge its features. 


Astrophotography  -  Nightscapes & Deep Sky Colors