We presented here the results of visual and telescopic observations of
-Cygnid stream made by CMW observers in years 1995-1997. This
stream is not included in the IMO List of Visual Meteor Showers
(Rendtel
et al. 1995) due to the lack of photographic, video and radio data confirming its
presence. The only continuous (not visual) surveys are the Harvard Super
Schmidt Program of the 1952-54 period and the Harvard Radar Project in
the 1960's. Both have gaps in coverage due to weather or instrument
irregularities. Unfortunately the
-Cygnids seem to fall in such gaps.
McCrosky & Posen (1961) presented the orbital elements of 2529
meteors photographed simultaneously from two camera stations of the
Harvard Meteor Project. The mean number of meteors captured in periods
January-June and August-December is 221 events per month. The number
of meteors photographed in July is only 102. It is over two times
smaller than in other months and certainly it is the reason of lacking
the meteors from
-Cygnid stream in that project.
The similar situation occurred during the Harvard Radar Project.
However recent radio results obtained by Michael
Boschat from Dalhousie University in Canada
(Boschat 1998) showed clear
enhancement of radio echoes in days 1998 July 19-20.
Analysis of 2748 paths of meteor events observed in July
1995, 1996 and 1997 allowed us to obtain the basic properties of the
stream. The geocentric velocity of the -Cygnid events
is
km s-1 and daily drift of
the radiant
,
.The coordinates of the center of the radiant
of
-Cygnid stream are
and
.
We performed a similar analysis for 234 telescopic meteors plotted also by CMW observers. The parameters of the stream are in very good agreement with the results derived from visual data.
Our results are also consistent with visual observations by Denning (1919) and Jenniskens (1994) and the photographic results obtained by Babadzhanov & Kramer (1965).
From magnitude distribution of 738 -Cygnids we obtained the
population index r equal to
which is in good agreement
with previously obtained value r=2.7 (Jenniskens 1994).
The velocity distributions of 754 -Cygnids and 4339 sporadics are
different, with a probability higher than 0.999 which gives another proof
for reality of the
-Cygnid stream.
From visual observations made by CMW members during the years 1995-1997 we
obtained the clear activity profile of the -Cygnid stream.
Meteors belonging to this shower were detected from June 30 to July 31
with clear maximum near July 18 (
). The
maximal ZHRs reached the level
. These results are in very
good agreement with results presented by Jenniskens (1994) who obtained
and
.
In spite of making many photographic exposures we still have no photographic confirmation of this stream. To confirm of disprove our results further visual, telescopic and particularly video and photographic observations are clearly needed.
Acknowledgements
We would like to thank to all observers who sent
us their observations. We are especially
grateful to Prof. Jerzy Madej for helpful discussions, reading and
commenting on the manuscript and also to Dr. Jacek Chooniewski for
many helpful hints. This work was supported by KBN
grants 2 P03D 020 11 and 2 P03D 002 15 to A. Olech.
Copyright The European Southern Observatory (ESO)