NGC6826 "Blinking Planetary"
Planetary Nebula in Cygnus
NGC6826 is called the "Blinking Planetary" because of a curious effect many people note while visually observing this nebula with small to modest sized amateur telescopes. Directly looking at the central star seems to cause the surrounding nebula to almost disappear; but when looking just off to the side, using what is known as "averted vision", the nebula clearly comes back into view. "Averted vision" takes advantage of a more light sensitive area of the retina, and combined with the difference in brightness between NGC6826's nebulosity and it's central star, produces a "blinking off and on" effect of the nebula as you look directly at and then just away from it.
Exposure Data: A SBIG ST-237 CCD image of 34:10:8:12 minute LRGB exposures at f/11 with a 12" SCT
Location and Date: Saugus, MA on 7-3-01
This image is a result of a collaboration with Sean Walker, who also did the bulk of the processing.
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