NGC 6772 in Aquila
July 2026 - Nebula and Cluster of the Month
July brings the northern Milky Way to its midnight transit, making it more accessible and for longer than at any other time of the year. It arches high above, sweeping through Cassiopeia, Cepheus, Cygnus, Vulpecula, Aquila, Scutum, Sagittarius and Scorpius, where it is lost beneath the horizon.
These constellations are abundant in two main types of object; open clusters and planetary nebulae. Aquila alone boasts ten NGC-listed planetary nebulae. There is one IC-listed planetary and the Strasbourg-ESO catalogue adds a further sixty. Plenty for the planetary nebula hunter to aim for here, then.
This month, we’ll be looking at one of the brighter planetary nebulae in Aquila, NGC 6772. It was first seen by William Herschel on the night of 17 July 1784. He described it as Very faint. Of equal light. Round, 1’ in diameter, in the midst of numberless stars of the milky way.
By Of equal light
, Herschel means that there is no discernible variation of brightness across the object. It doesn’t get noticeably brighter in the middle, for example.
He classed it as a planetary nebula (not by the definition of that term that we use today) and gave it the catalogue number 14 H.IV.
NGC 6772 is not, it must be admitted, a very bright object. It shines at magnitude 12.7, and being moderately large (a little over 1’ in diameter) has a fairly low overall surface brightness, meaning it may look rather fainter than its quoted magnitude.
Whilst this may prove a difficult object for novice observers, more experienced ones will find this to be a rewarding, if subtly challenging object. If you can, search it out using a lower power eyepiece with a large exit pupil. Use of an OIII filter will also likely be necessary to identify the object. This object responds very well to OIII filtration, especially under good skies. Once found, higher powers can be employed. Experienced observers generally describe it as a diffuse, circular glow with, at best, only slight central brightening.
I managed to observe it in 2014 with my 12” Newtonian from my considerably less than perfect home site. The observation is reproduced here. My journal for the night notes that I found it large but very dim. It was barely discernible without the OIII filter in place. Even with the filter, it was still difficult. It appeared not quite round being slightly elongated North-South. There was no variation in brightness seen across the surface of the object. I managed to push the magnification up to x450 using a x3 Barlow lens with a Plossl 10mm eyepiece, without losing sight of it. If anything, it became clearer and I made my drawing at this magnification. There was no hint of a central star, but as this only glimmers dimly at magnitude 18.2, that cannot be considered surprising.
One thing that makes NGC 6772 particularly interesting is its evolutionary state. Deep imaging reveals extensive outer structures and a distorted halo produced by interaction with the surrounding interstellar medium. Professional studies using infrared observations have found evidence that the outer envelope is being shaped and fragmented as the nebula moves through interstellar gas. These dramatic features are only visible on deep images, but knowing they are present adds an extra dimension to visual observation.
From a purely visual standpoint, NGC 6772 is best regarded as a challenging object suitable for a moderately experienced observer, or for a newer observer keen to challenge themselves and develop their observing technique. For observers working through the lesser-known planetary nebulae of Aquila, it is a satisfying target whose detection depends more on observing skill, transparency and filter technique than on telescope size alone. Under a dark British summer sky with a good OIII filter and an aperture of 10—12 inches (250—300mm) or larger, it presents itself as a delicate ghostly sphere suspended among the dense stars of the Milky Way.
| Object | RA | Dec | Type | Magnitude |
|---|---|---|---|---|
| NGC 6772 | 19h 14m 37s | -02° 42’ | Planetary nebula | 12.7 |
If you'd like to try out the Clear Skies Observing Guides (CSOG), you can download observing guide for the current Cluster of the Month without the need to register. CSOG are not associated with the Webb Deep-Sky Society but the work of Victor van Wulfen.
