We present a comprehensive study of a possible alpha -Cygnid meteor shower. Based on visual and telescopic observations made by Polish observers we estimate basic parameters of the stream. Activity of alpha -Cygnids lasts from around June 30 to July 31 with clear maximum near July 18 (solar longitude lambda_sun =116.5(deg) ). 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(-1) , and for the drift of the radiant (in units (deg) /day) equal to Delta alpha =+0.6 Delta delta =+0.2. Center of the radiant for the moment of maximum is alpha =302.5(deg) delta =+46.3(deg) . 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 alpha -Cygnids and 4339 sporadic events by chi (2) 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 chi (2) parameter were obtained for the geocentric velocity equal to 40 km s(-1) and for the drift of the radiant (in units (deg) /day) equal to Delta alpha =+0.6 Delta delta =+0.2. The center of the radiant for moment of maximum is alpha =304.9(deg) delta =+46.2(deg) . In spite of making many photographic exposures we still have no photographic or video confirmation of the existence of this stream.
Astronomy and Astrophysics Supplement Series
- Pub Date:
- March 1999
- INTERPLANETARY MEDIUM;
- accepted for publication in Astronomy and Astrophysics, Supplement Series, 8 pages with 4 figures