  Very short pulses of x-ray free-electron lasers opened the way to obtain
diffraction signal from single particles beyond the radiation dose limit. For
3D structure reconstruction many patterns are recorded in the object's unknown
orientation. We describe a method for orientation of continuous diffraction
patterns of non-periodic objects, utilizing intensity correlations in the
curved intersections of the corresponding Ewald spheres, hence named Common Arc
orientation. Present implementation of the algorithm optionally takes into
account the Friedel law, handles missing data and is capable to determine the
point group of symmetric objects. Its performance is demonstrated on simulated
diffraction datasets and verification of the results indicates high orientation
accuracy even at low signal levels. The Common Arc method fills a gap in the
wide palette of the orientation methods.

Data Analysis, Statistics and Probability