As summer transitions to fall, Cygnus flies directly overhead. There, atop the firmament, a multitude of gems wait for us, including nice double and triple star systems. One of these notable triples is 31 Cygni, also known as Omicron Cygni. None of the stars in the system is physically related, but they exhibit remarkable similarities. Of note, the primary and secondary stars (o1 and o2 Cyg) are both large orange giants with one peculiar addition: Each orange giant has a hot blue star orbiting it.
When observing, you’ll notice the trio sits on a bed of fainter Milky Way stars. During my 2021 observation, the orange color of the primary star hit me right away (see description below).
My Observations
| Date | September 1, 2021 |
| Time | 10:10 p.m. |
| Location | Seattle, WA |
| Magnification | 127x |
| Scope | Meade 8″ SCT |
| Eyepiece | 16mm |
| Seeing | Average |
| Transparency | Average, light haze |
The bright orange star in 31 Cygni pulls strongly on my imagination—it’s alluring and seemingly 3D in nature. Perhaps this is so since this trio floats on the Milky Way river. Not sure exactly why, but at this moment, I’m visualizing a distant train with an orange headlamp coming my way, but it’s so far away that I cannot hear the horn.
Key Stats
| Constellation | Cygnus |
| Best Viewing | Summer |
| Visual Magnitude | +3.8 | +7 |
| Absolute Visual Magnitude | -3.4 |
| Distance from Earth | 880 ly |
| Separation | 36.5″ | 9890 AU |
| Orbital Period | 3784 Days |
| Milky Way Location | Orion Spur |
| My Viewing Grade | B |
Sources and Notes
Banner photo of 31 Cygni is by Jefffischer10 and provided in agreement with the Creative Commons Attribution-Share Alike 4.0 International license.
Sketch by Wayne McGraw
AKA: 31 Cyg, Omicron1, 30 Cyngi, 32 Cygni, SAO 49337
The Garden Astronomer 