[en] In the presented paper experiments are discussed related with studies of the coherence of dipolar-exciton Bose condensate in GaAs/AlGaAs heterostructure containing a wide single GaAs quantum well and Schottky gate. Dipolar excitons were photoexcited in the ring trap arising along the perimeter of a window in metal gate under applied electrical voltage. With the help of two-beam interference technique related with interference addition of luminescence-light amplitudes and subsequent analysis of correspondent 1-st order correlators both temporal (longitudinal) and spatial (transversal) coherence of exciton condensate have been explored. The transversal coherence length of exciton condensate has been found to exceed considerably thermal de Broglie wavelength of a dipolar exciton. Coherence of the exciton Bose condensate is confirmed also by experimental studies of the luminescence intensity correlations.