Open Cluster IC 1311

IC 1311
IC 1311: Open cluster in Cygnus; 500 mm Cassegrain 3625 mm f/7.2, SBIG STL11K; 90+3*40 min LRGB; Bernese Highlands; © 2015 Radek Chromik [32]


The open star cluster IC 1311 was discovered on 6 October 1893 by the British astronomer Thomas Espin. He described it as «very faint, in a circle of stars». The astronomer Robert Trümpler, who comes from Switzerland and lives in the USA, classified this star cluster as type II3rn: II = somewhat weaker concentration, 3 = some bright, many weak stars, r = rich (100 ... 500) stars, n = connection with nebula. [196]

Physical Properties

IC 1311
IC 1311: Image taken with the 4 m Mayall telescope on Kitt Peak [377]

The cluster has around 850 stars and its age is estimated to be around 1.6 billion years. Due to the reddening caused by interstellar gas and dust, the distance information is rather imprecise: They range from 5.8 kpc to 15.8 kpc (18900 to 51'000 light years). [146, 376]

IC 1311 is located on the north-western edge of the large, faintly red glowing Gamma Cygni Nebula (IC 1318), which is stimulated to glow by the strong ultraviolet radiation of massive, hot, blue stars. But probably the star cluster IC 1318 has no connection with this H-II region. If its distance information is correct, it would have to be far in the background. The star Sadr (γ Cygni) is 1'800 light years away. [149]

Revised+Historic NGC/IC Version 22/9, © 2022 Dr. Wolfgang Steinicke [277]
Designation IC 1311
Type OCL (II3rn)
Right Ascension (J2000.0) 20h 10m 48.0s
Declination (J2000.0) +41° 10' 24"
Diameter 5 arcmin
Visual magnitude 13.1 mag
Metric Distance 5.333 kpc
Identification, Remarks OCL 173; COU 45; URA 50

Finder Chart

The open star cluster IC 1311 is located in the constellation Cygnus. The best observation time is March to December.

Finder Chart Open Cluster IC 1311
Open Cluster IC 1311 in constellation Cygnus. Charts created using SkySafari 6 Pro and STScI Digitized Sky Survey. Limiting magnitudes: Constellation chart ~6.5 mag, DSS2 close-ups ~20 mag. [149, 160]

Objects Within a Radius of 15°