| Emission nebula | |
|---|---|
| Planetary nebula | |
 | |
| Observation data:J2000epoch | |
| Right ascension | 19h 44m 48.2s[1] |
| Declination | +50° 31′ 30.3″[1] |
| Distance | ~2000 ly |
| Apparent magnitude (V) | 8.8[2] |
| Apparent dimensions (V) | 27″ × 24″[2] |
| Constellation | Cygnus |
| Physical characteristics | |
| Radius | 0.22 x 0.20[2] ly |
| Designations | HD 186924, SAO 31951,[1]Caldwell 15 |
| See also:Lists of nebulae | |
NGC 6826 (also known asCaldwell 15) is aplanetary nebula located in theconstellationCygnus. It is commonly referred to as the "Blinking Planetary", although many other nebulae exhibit such "blinking". When viewed through a small telescope, the brightness of the central star overwhelms the eye when viewed directly, obscuring the surrounding nebula. However, it can be viewed well usingaverted vision, which causes it to "blink" in and out of view as the observer's eye wanders.
A distinctive feature of this nebula are the two bright patches on either side, which are known asFast Low-Ionization Emission Regions, or FLIERS. They appear to be relatively young, moving outwards at supersonic speeds.[3]
HD 186924 is the central star of the planetary nebula. It is anO-type star with aspectral type of O6fp.[1]
