| Nebula | |
|---|---|
 NGC 6644, as seen by theHubble Space Telescope | |
| Observation data: J2000epoch | |
| Right ascension | 18h 32m 34.73s |
| Declination | −25° 07′ 45.7″ |
| Distance | 20,000 ly |
| Apparent dimensions (V) | 0.20' |
| Physical characteristics | |
| Absolute magnitude (V) | 10.7 |
| See also:Lists of nebulae | |
NGC 6644 is abipolar planetary nebula located in the constellationSagittarius. NGC 6644 was discovered by American astronomerEdward Charles Pickering in 1880. With an apparentvisual magnitude of 10.7, a telescope with an aperture of at least 150millimeters must be used to observe it. The nebula is located about 1.1 degrees northeast of the starLambda Sagittarii. According to the most recent studies (2010), the distance of NGC 6644 is 6.131 ± 1.226 kpc (∼20,000 light-years).[1][2][3][4]