Open cluster NGC 6910 shines near Gamma Cygni

NGC 6910 is a bright open cluster in Cygnus the Swan, visible overnight as the Summer Triangle flies high around local midnight.

This image shows the region around Gamma Cygni, the bright star below center. Visible are IC 1318 (the red glow) and the small open cluster NGC 6910, to Gamma Cyg’s lower right. Credit: gianni (Flickr, CC BY-SA 2.0)

The Summer Triangle asterism, composed of Altair, Vega, and Deneb, is prominent in the southwestern sky around midnight.
The Summer Triangle encompasses a large area (415 square degrees) rich in Milky Way features.
NGC 6910, a young open cluster within the Cygnus OB9 Association, is a notable object within the Summer Triangle, visible with medium-sized telescopes.
NGC 6910, located near Gamma Cygni (Sadr), is part of a larger star-forming complex within the IC 1318 hydrogen cloud, approximately 5,600 light-years distant.

Nights are slowly shortening, but even as summer begins to wind down, the Summer Triangle still flies high in the sky overnight. Formed by three bright stars, this large asterism is highest around local midnight, when its center — through which the plane of the Milky Way flows — is some 70° high above the southwestern horizon.

At that time, if you are facing southwest, the lowest star in the Triangle is magnitude 0.8 Altair in Aquila the Eagle. Some 34° to its northwest (upper right) is magnitude 0.0 Vega, the alpha star of Lyra the Lyre. And about 24° to Vega’s upper left (northeast) is the third point in the Triangle and its highest star at this time, magnitude 1.3 Deneb in Cygnus the Swan. Covering some 415 square degrees — that’s more than 2,000 Full Moons — the Summer Triangle contains within its bounds a rich region of the Milky Way with plenty to see.

One such target is NGC 6910, a young open cluster shining at magnitude 7.5. It’s located about 0.5° from magnitude 2.2 Gamma (γ) Cygni, also called Sadr. This grouping looks best under higher magnification, showing up well in medium-sized telescopes, though it can be picked up in smaller scopes as well. With about 70 stars in total, this cluster is part of a much larger star-forming complex called the Cygnus OB9 Association, which lies some 5,600 light-years away. It is located within a cloud of hydrogen cataloged as IC 1318, which can be seen in deep-sky photographs of the region.

Sunrise: 6:14 A.M.
Sunset: 7:54 P.M.
Moonrise: —
Moonset: 4:01 P.M.
Moon Phase: Waning crescent (33%)
*Times for sunrise, sunset, moonrise, and moonset are given in local time from 40° N 90° W. The Moon’s illumination is given at 12 P.M. local time from the same location.

For a look ahead at more upcoming sky events, check out our full Sky This Week column.