Alpha Cygnids - a possible July minor meteor shower

¹ Warsaw University Observatory, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
² Comets and Meteors Workshop, ul. Sokolicz 3/59, 01-508 Warszawa, Poland

Send offprint request to: Arkadiusz Olech

Received: 23 June 1998
Accepted: 6 November 1998

Abstract

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 ). Maximal Zenithal Hourly Rates (ZHRs) are equal to . The structure of the radiant analyzed by radiant software is most compact for geocentric velocity of the events equal to 41 km s^-1, and for the drift of the radiant (in units °/day) equal to . Center of the radiant for the moment of maximum is . We derive population index r equal to from magnitude distribution of 738 possible members of the stream. Comparing the velocity distributions of 754 possible α-Cygnids and 4339 sporadic events by and Kolmogorov-Smirnov tests we conclude that both distributions are different with a probability very close to 1.0. Telescopic observations strictly confirm the results obtained from visual observations. The smallest values of parameter were obtained for the geocentric velocity equal to 40 km s^-1 and for the drift of the radiant (in units °/day) equal to . The center of the radiant for moment of maximum is . In spite of making many photographic exposures we still have no photographic or video confirmation of the existence of this stream.