M29 is a binocular and telescope open cluster that's situated in the highly crowded Milky Way region of Cygnus. The cluster isn't particularly impressive in terms of brightness, number of stars and compactness but certainly worth a look due to its location and unusual shape. It appears like a squashed dipper that loosely resembles the main stars of Ursa Major. Adding to the view is a stunning backdrop of literally thousands of distant Milky Way stars.
M29 was one of Charles Messier original discoveries, which he catalogued on July 29, 1764. He described it as "a cluster of 7 or 8 very small stars below Gamma Cygni". What is surprising in such a rich constellation is that Messier recorded only two deep sky objects, the other being open cluster M39.
Although M29 is unremarkable, it's easy to find since it's positioned just 1.75 degrees south of Sadr (γ Cyg). At mag. +2.23, this is the second brightest star in the constellation. The cluster is best seen from the Northern Hemisphere, where it appears high in the summer sky.
M29 is visible in binoculars but best seen at low to medium powers through telescopes. When viewed through an 80mm (3.1-inch) scope, the stubby big dipper shape of the main stars is clearly visible. Remarkably, despite its prominent location, M29 does stand out against the background "wall" of stars. However, the cluster is small. It covers just 7 arc minutes, which is about a quarter of the diameter of the full Moon. An advantage of such a small apparent size is that it's possible to push up the magnification without the cluster overspilling the eyepiece field of view.
Through larger scopes, M29 appears much the same although more members are visible along with many non-cluster stars. In the vicinity of M29, there is some diffuse nebulosity, which can be detected in images and photographs.
In total M29, contains about 50 member stars of which 6 are brighter than magnitude +9.5. Its distance from Earth is uncertain due to light absorption by surrounding interstellar matter. The current estimate is about 4,000 light-years.
M29 Data Table
|Object Type||Open cluster|
|RA (J2000)||20h 23m 58s|
|DEC (J2000)||+38d 30m 28s|
|Apparent Size (arc mins)||7.0 x 7.0|
|Age (years)||10 Million|
|Number of Stars||50|
|Other Name||Collinder 422|