Object: U Cygni

Spectral class
: Cygnus
: 21:19:36 / +47.53.42
: 5.9-12.1
: R
: Red
Detail sketch:
Date / Time
Observing Location
Seeing / Transparency
Magnification / Field of View '
: 18/08/09 / 23:00
: Landgraaf
: 3 / 5
: Orion Optics UK 300 mm
: 22 mm Nagler type 4
: 72 / 68
U Cygni

Observing Report

I read a few reports on the Internet last week, about U Cygni being a spectacular blood red star at the moment. On the night of the 18th of august it was clear outside, so I decided to go for it! I first tried to locate it with my 15x80 binoculars and the SkyWindow, but without success. But with the 300mm Dobson and the 35mm Panoptic (46x) the dim red star was immediately visible, next to an 8th magnitude white star (HIP100230). A striking pair with a beautiful contrast. U Cygni and HIP100230 are separated by only 1 minute of arc. As usual, I first tried all possible magnifications, but the 22 Nagler showed this little gem at its best. As other observers stated this week, U Cygni indeed was bright red, like a sparkling drop of blood. Simply amazing to really see a star as red as U Cygni with your own eyes. Very impressive!

The contrast with its surroundings was somehow optimal with 22mm Nagler, giving a magnification of 72x and a field of view of 68'. A real bonus was that U Cygni fitted nicely into the same field of view with the magnitude 4 bright yellow-orange Omicron 2 Cygni (or 32 Cygni). After observing and enjoying the field the field of view for 15 minutes, I noticed that HIP 100230, the white "companion" of U Cygni wasn't really white, but a bit yellowish. At the end of my observing session I made a sketch. I only plotted the most important starts, because there were just too many field stars visible.


U Cygni is a Class R, carbon type pulsating red giant, a Mira type variable with a period of around 463 days. The magnitude range is huge, from 5.9 to 12.1. At the moment I estimate it's around magnitude 10 to 11. Mira's are among the coolest, largest and most luminous red giants.

U Cygni was very easy to locate, because I was already very familiar with its surroundings. I have observed the colorful Cygnus triple known by the name of Omicron 1 Cygni many times in the past, using my 15x80 binoculars. Together with Omicron 2 Cygni (or 32 Cygni) it forms a stunning celestial sight. Just 50' east of the bright yellow-orange Omicron 2 Cygni I found U Cygni. On my sketch you see Omicron to the right, forming a triangle with two other white field stars. U Cygni can be seen on the right, together with HIP 100230.