Alpha Cygnids - a possible July minor meteor shower

We present a comprehensive study of a possible α-Cygnid meteor shower. Based on visual and telescopic observations made by Polish observers we estimate basic parameters of the stream. Activity of α-Cygnids lasts from around June 30 to July 31 with clear maximum near July 18 (solar longitude λ = 116.5◦). Maximal Zenithal Hourly Rates (ZHRs) are equal to 3.6± 1.2. The structure of the radiant analyzed by radiant software is most compact for geocentric velocity of the events equal to 41 km/s, and for the drift of the radiant (in units ◦/day) equal to ∆α = +0.6 ∆δ = +0.2. Center of the radiant for the moment of maximum is α = 302.5◦ δ = +46.3◦.We derive population index r equal to 2.55±0.14 from magnitude distribution of 738 possible members of the stream. Comparing the velocity distributions of 754 possible αCygnids and 4339 sporadic events by χ and KolmogorovSmirnov tests we conclude that both distributions are different with probability very close to 1.0. Telescopic observations strictly confirm the results obtained from visual observations. The smallest values of χ parameter we obtained for the geocentric velocity equal to 40 km/s and for the drift of the radiant (in units ◦/day) equal to ∆α = +0.6 ∆δ = +0.2. The center of the radiant for moment of maximum is α = 304.9◦ δ = +46.2◦. In spite of making many photographic exposures we still have no photographic or video confirmation of the existence of this stream.