Disrupting the Cygnus Star Cloud

NGC 6871
Sketch and Details by Rony De Laet

On a dark summer night, the Milky Way itself is a magnificent deep-sky object for the naked eye observer. The subtle glow of the star clouds and nebulae offers an intriguing sight. One of the brighter clouds, visible from my latitude, is the Cygnus Star Cloud. The sky between Albireo and Gamma Cygni appears like a glowing oval. An interesting feature is displayed by the star field just NE of Eta Cygni. The smooth Milky Way glow seems to be disrupted at that location, as it shows a mottled appearance to the unaided eye. The binocular view reveals a multitude of star associations. The brightest stars, beside Eta, are 27, 28 and 29 Cygni (see the labelled sketch). Some of the star associations are real clusters. Such is the case with NGC 6871, which appears like a 1 degree long star chain, starting S of 27 Cygni, and running first N and then NE through 27 Cygni at 28 Cygni. It is unclear to me where NGC 6871 actually ends. A nice double star, called Beta440, can be found just S of 27 Cygni.
A small cluster, called Biurakan 1, can be found just E of Beta440.
Another cluster, NGC 6883 can be seen at 1° E of 27 Cygni. My pair of binocular just show NGC6883 as a small brightening in the Milky Way glow.
Another interesting star chain starts with 29 Cygni, which first runs S and then bends to the W and back to the N.
Many of these stars in this particular field are very young supergiants, and members of the Cygnus OB3 association, making part of the Orion-Cygnus Spiral Arm at a distance of 5.700 l-y.

Site : Bütgenbach, Belgium
Date : July 2, 2008
Time : around 00.30 UT
Binoculars : Bresser 8×56
FOV: 5.9°
Filter : none
Mount : Trico Machine Sky Window
Seeing : 3,5/5
Transp. : 4/5
Nelm : around 5.8
Sketch Orientation : N up, W right.
Digital sketch made with Photo Paint, based on a raw pencil sketch.

(Note: if the sketch does look too dark on your monitor, try to darken the room.)