NGC 6781 (Aquila)
The planetary nebula NGC 6781 ("Snowglobe Nebula") in the constellation Aquila
Fig. 1 - Shining under the harsh ultraviolet radiation from the progenitor star: The planetary nebula NGC 6781 in Aquila, photographed with an 8-inch f/5 Newtonian reflector on a ZWO AM5 mount.
| Object name: | Constellation: | Coordinates: | Apparent size: | Visual brightness: |
|---|---|---|---|---|
| NGC 6781 | Aquila | 19h18m / +06°32' | 1.9' x 1.8' | 11.4 mag |
NGC 6781 (Snowglobe Nebula) is a planetary nebula in the constellation Aquila. Stars like our Sun lack the mass for a dramatic supernova ending, but they still go out with flair—shedding colorful gas shells called planetary nebulae before becoming dense, Earth-sized white dwarfs. NGC 6781 is a fine example of this stage of stellar evolution.
The central white dwarf is the remnant of a star that originally possessed about 2.5 times the mass of the Sun. After expelling its outer layers, it began cooling roughly 9,400 years ago, creating the planetary nebula we observe today.
Although NGC 6781 appears nearly circular in photographs, astronomers believe its true shape is closer to a hollow cylinder or barrel. Seen almost directly along its axis from Earth, this three-dimensional structure creates the nebula's distinctive ring-like appearance.
NGC 6781 lies at a distance of 1,500 light-years from the Sun, measures approximately two light-years across and was discovered in 1788 by the Anglo-German astronomer William Herschel (source: Wikipedia).
Technical Details:
Exposure time: 4h 30min (90x3min)
Gain: 100
Temperature: -10°C
Date: June 21/22 and June 28/29, 2025
Processing: Astro Pixel Processor (APP) and Photoshop
Calibration: Darks, flats, and bias
Equipment:
Cooled ASI 2600MC Pro camera, TeleVue Paracorr Type II coma corrector, 8" f/5 "ONTC" Newtonian telescope, ZWO AM5 Strain Wave Mount, ZWO OAG-L off-axis system, ASI 174MM Mini guide camera, ASIAIR Plus
NGC 6781 was also captured with a 16-inch dobsonian on an equatorial platform, using a DSLR camera. The image can be seen here.
Fig. 2 - Search chart for NGC 6781. Copyright 2025 'The Mag-7 Star Atlas Project', www.siaris.net.