NGC 6826 - the Blinking Nebula (Caldwell 15)
The name refers to the nature of human vision and not that of the nebula at all! The nebula appears to "blink" because it is dim. Human eyeballs have their least sensitive cells in the center of the fovea. Thus, staring at this object makes it appear to dim (or even disappear) whereas using "averted vision" makes the nebula look brighter.
NGC 6826 24 Apr 07
10:11 - 10:23 hrs
Meade LX200GPS 14"
Meade DSI IIC camera
100 exposures at unrecorded duration, but probably 5.7 seconds or 8 seconds