Guide to U Cephei

A circumpolar eclipsing variable with a deep (2.5 magnitude) eclipse.

Tracie Heywood’s light curve showing a primary eclipse

The primary eclipse occurs when the fainter star in the system passes in front of the brighter star.

The eclipses are “flat-bottomed”, indicating that a total eclipse is taking place.

The orbital period of U Cephei is approx 2.493 days. Hence, if you see an eclipse on a particular night, another will be visible at a similar time of night 5 nights later.

Extreme brightness range 6.7 – 9.3
More typical range always the same
Period of variation 2.493 days
Frequency of observation Every 30 minutes during an eclipse
Observe using 50mm binoculars will suffice for most of the time, but larger binoculars may be required during the deepest part of the eclipse
Visibility Can be observed all year round (although there may be a spell during the spring and/or summer when no eclipses are falling during the hours of darkness)


The following finder charts show the location of U Cephei. You can follow its brightness changes by comparing its brightness with that of the labelled comparison stars on the second chart.

U Cephei


Chart for U Cephei