| Nebula | |
|---|---|
 NGC 6644, as seen by the Hubble Space Telescope | |
| Observation data: J2000 epoch | |
| 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 |
NGC 6644 is a bipolar planetary nebula located in the constellation Sagittarius. NGC 6644 was discovered by American astronomer Edward Charles Pickering in 1880. With an apparent visual magnitude of 10.7, a telescope with an aperture of at least 150 millimeters must be used to observe it. The nebula is located about 1.1 degrees northeast of the star Lambda 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]
- ^ "NGC 6644 - Planetary Nebula in Aquila". The Sky Live. Retrieved October 23, 2024.
- ^ Chih-Hao, Hsia; Kwok, Sun; Zhang, Yong; Volk, Kevin (December 2010). "An Optical-infrared Study of the Young Multipolar Planetary Nebula NGC 6644". Harvard. Retrieved October 23, 2024.
- ^ Astronomy, Go. "NGC 6644 | planetary nebula in Sagittarius | New General Catalogue". Go-Astronomy.com. Retrieved 2024-10-23.
- ^ Aller, Lawrence H.; Keyes, Charles D.; Feibelman, Walter (1988-02-01). "Two compact planetary nebulae of moderate excitation - NGC 6565 (3-4.5 deg) and NGC 6644 (8-7.2 deg)". Astronomical Society of the Pacific, Publications. 100. ISSN 0004-6280.