Gamma Delphini is a double star system in the constellation Delphinus. It’s best viewed in summer and early autumn.
While not as famous or startling as the double star Albireo, Gamma Delphini is a worthy binary not to be missed, as the double stars Gamma-1 and Gamma-2 make a colorful pair. In my case, I observed the pair as one being yellow and the other orange. However, others have observed the smaller, fainter star as blue, yellow, or green.
According to Jim Kaler, from his site Stars, if you could stand on the Gamma-1 star, the Gamma-2 star would look as bright as 100 of our full moons. They are 343 AU apart.
My Observations
| Date | November 1, 2020 |
| Time | 7:00 p.m. |
| Location | Seattle, WA |
| Magnification | 203x |
| Scope | Meade 8″ SCT |
| Eyepiece | 10mm |
| Seeing | Above Average |
| Transparency | Above Average |
This is a fairly binary choice due to the distinct colors used: orange and yellow. The top star, I believe, is yellow, while the bottom is orange.
Other Dates Observed:
Also observed on October 8, 2021, at 8:10 p.m. Notes: This time, the secondary star appears more white/greenish to me, confirming to me how stars like these can appear different when viewed on different nights. There is some haze in the region right now, so perhaps this is contributing to my perception of it as more greenish tonight.
Key Stats
| Constellation | Delphinus |
| Best Viewing | Autumn |
| Visual Magnitude | +5.1 | +4.4 |
| Absolute Visual Magnitude | +2.0 |
| Distance from Earth | 126 ly |
| Separation | 8.8″ | 343 AU |
| Orbital Period | 3249 years |
| Milky Way Location | Orion Spur |
| My Viewing Grade | A- |
| Designations | SAO 106477, γ Delphini, HD 197964, 12 Delphini |
Sources
Banner shared under the Creative Commons Attribution-Share Alike 4.0 International license. Photo by David Ritter. Details here.
Sketch by Wayne McGraw
The Garden Astronomer 
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