This shower is active during June 10 to 21, producing predominantly blue and
white meteors at a maximum hourly rate of 8 per hour on June 15 (Solar
Longitude=84.5 deg). At maximum the radiant is located at RA=278 deg, DECL= deg.
The average observed magnitude of this shower is near 3, while about 32% of the
meteors leave trains.
History
This meteor shower was discovered on the evening of June 15, 1966, by Stan
Dvorak (California) while camping out in the San Bernardino mountains. His
attention had been drawn to the region of Lyra by a very bright meteor that
moved swiftly to the northeast through that constellation. Another meteor was
noted a short time later and Dvorak began plotting additional meteors. After 1
1/2 hours he had managed to plot 16 meteors, of which 13 appeared to originate
from a hitherto unknown radiant located at RA=278 deg, DECL= deg. Just a few
hours later, F. W. Talbot (Cheshire, England) independently discovered the
radiant at RA=275.5 deg, DECL= deg, and noted an hourly rate near 9.
Moonlight from a waning moon interfered with observations in 1967, but, in
June 1968, confirmation of this shower's existence came from Richard Nolthenius
(Hacienda Heights, California). During one hour on the 15th, he detected 8 June
Lyrids, while a similar hour on the 17th revealed 7. Observations of this shower
have continued annually ever since, however, to date, the most elaborate study
of this shower was made from observations obtained during 1969.
Observations from 46 observers, totalling 172 man-hours, were gathered and
analyzed by Keith B. Hindley of the British Astronomical Association. The
observations covered the period of June 11.5 to 21.0 (Solar Longitude=80.2 deg
to 89.2 deg) and the total number of June Lyrids observed was 363. Against a
fairly constant sporadic meteor rate of 8.7 per hour, the June Lyrids displayed
a broad maximum of about 6 per hour during June 13 to 17, with a sharp peak of 9
per hour on June 16.0 (Solar Longitude=84.5 deg). The average magnitude was
found to be 2.0 and 32% of the shower's meteors showed persistent trains. Colors
displayed a prominence of white, as did sporadic meteors, however, there was
also a large number of blue meteors. The exact percentages of colors seen among
the June Lyrids were as follows: 33%, blue, 52%, white, 9%, yellow, and 6%,
orange-red.
The average radiant, as determined by Hindley, was found to be RA=278 deg2
deg, DECL= deg3 deg. From this position, a parabolic orbit was calculated, which
revealed a close, but "not convincing" similarity to comet Mellish (1915 II).
This comet possesses a slightly hyperbolic orbit with an eccentricity of 1.0002.
A radar orbit obtained by Zdenek Sekanina from observations made at Havana,
Illinois, in 1969, actually seemed to strengthen the similarity between the June
Lyrids and 1915 II, except for the fact that the radar orbit revealed a period
of 2.94 years. These orbits are compared later.
Although observations continued after 1969, there seemed an indication that
the meteor rates of 8 or 9 per hour had vanished. In 1971, about 215 hours of
observations were acquired by 26 observers from Canada and the United States.
The shower's ZHR irregularly varied during the period of June 10 to 24, with
maximum peaks of 1.3 to 3.5. The radiant of the stream was determined from 37
meteors plotted by an Ottawa observing group from observations made during June
14 to 17, with the result being RA=278.3 deg, DECL= deg.
In 1972, the shower again showed a poor return. Meteor News combined
the observations of 20 observers, made during June 9 to 22, and found the
maximum ZHR to be only 2.3---a value that came on June 15/16. What the
observations also revealed were activity levels between 1.2 and 1.3 during June
12 to 15, which suddenly jumped to 2.3, then rapidly fell to only 0.3 by the
night of June 18/19. Thus, the shower's date of maximum and variation of
activity levels closely reflected those noted in 1969, but the ZHRs were
typically down by about 6 or 7 meteors per hour!
Observations in 1974 indicated a resurgence of activity. The shower's
discoverer, Dvorak, observed on four nights during mid-June, with the following
average hourly rates (not ZHRs) being noted: June 14/15, 2.9, June 15/16, 6.5,
June 16/17, 6.2, June 17/18, 2.3. Dvorak added that the meteors moved swiftly,
with the majority being bluish-green. Also, in 1974, Nolthenius, Alan Devault
and Bob Fischer (all of California) observed during 7 nights between June 9 and
22. Overall, they observed 32 June Lyrids, with the average magnitude being
determined as 3.09. Slightly less than half of their total number of June Lyrids
were seen on the shower's night of maximum (June 15/16). The average number of
meteors seen from this radiant was 4 per hour.
During 1975, observations were quite scarce. Between June 6 and 15, Norman
W. McLeod III (Florida) saw only 2 June Lyrids, while, during the period June 9
to 14, Mark Adams (Pennsylvania) noted 5 members, with 4 coming in less than 3.5
hours on the final date of observation. Finally, Paul Jones (St. Augustine,
Florida) observed for 3 hours on the night of maximum and detected 20 June
Lyrids.
Interest in the June Lyrids seems to have waned in the latter half of the
1970s and into the 1980s, with only a few individuals continuing to monitor the
shower annually---many of them rarely observing around the time of the shower's
established date of maximum. As is evident from the previously listed
observations, activity from this radiant can be virtually nonexistent on dates
other than June 15 and 16, due to the June Lyrids' very pronounced peak of
activity.
In 1979, observers in Texas observed on June 15/16 and 17/18, with meteors
being seen to reach nearly 2 per hour on the latter date. In Quebec, F. Roy
observed during June 16/17, 18/19 and 20/21 and noted 12 meteors in about 3.5
hours---certainly marking the most activity seen from this radiant since 1974.
During 1980, the enhanced rates still seemed present, with John West (Texas)
noting 18 meteors in only 5 hours on June 13/14 and 14/15. Since 1980, the
shower's activity has again dropped to maximum rates of about 1 per hour.
A search for pre-1966 observations of this shower has not revealed many
clues to the shower's history. From observations by Giuseppe Zeziolli, G. V.
Schiaparelli isolated 11 meteors observed on June 14, 1869, from a radiant of
RA=280 deg, DECL= deg. No convincing June Lyrid radiants were observed by
members of the American Meteor Society prior to 1966, nor were any observations
present among the extensive visual radiants obtained by A. S. Herschel, Alphonso
King, Cuno Hoffmeister or Ernst Opik.
Aside from the 1969 study by Hindley, studies of the June Lyrids have been
rare, with the only other information gathered on the individual meteors
involving the average magnitude. John West observed 59 June Lyrids during 1967
to 1982, and found the average magnitude to be 3.02. During 1967 to 1981, Rick
Hill (North Carolina) observed 65 June Lyrids and found the average magnitude to
be 2.71.