Two similar detached binary systems: AT and AZ camelopardalis

Photoelectric BV observations of AT Cam are presented. The O-C diagram of the times of light minimum shows a probable long-term variation in the period. Photometric solutions using the Wilson-Devinney method were made for both AT Cam and AZ Cam. Both are found to be detached systems, but the components are close to the critical surfaces. For AT Cam, there are two probable solutions around the mass-ratio, q=0.60 and 3.45, both giving a detached configuration. For AZ Cam, q=1.52, the primary eclipse is a partial occultation at an inclination i=80.5°. A brief discussion is given on their evolutionary stages, based on the fractional radii and the mass-ratios obtained.