This daylight shower occurs during May 20 to July 5. Maximum occurs on June
13, from an average radiant of RA=63 deg, DECL=+26 deg. Radar surveys have
revealed the activity of this shower to be near 40 per hour. The daily motion of
the radiant amounts to +1.1 deg in RA and +0.4 deg in DECL.
History
The Zeta Perseids were discovered in 1947 by operators of the radio
equipment at Jodrell Bank (England). Only rough details were available at that
time, with the duration being determined as June 2-17, and the radiant being
estimated as falling within the range of RA=52 deg to 62 deg, DECL=+15 deg.
Jodrell Bank observations continued during 1949 and 1950, with A. Aspinall and
Gerald S. Hawkins establishing a duration of June 1-16 and a typical radiant
diameter of less than 3 deg. The average radiant position was given as RA=61.6
deg, DECL=+23.8 deg.
A radar study was conducted by B. L. Kashcheyev and V. N. Lebedinets during
1960, using equipment at the Kharkov Polytechnical Institute (USSR). The
analysis revealed a duration of May 4 to June 19, with the nodal passage coming
on June 2 (Solar Longitude=71 deg), and the average radiant being RA=52 deg,
DECL=+23 deg.
During the first session of the Radio Meteor Project, Zdenek Sekanina
determined the duration as May 20 to June 21. The date of the nodal passage was
given as June 8.9 (Solar Longitude=77.6 deg), at which time the radiant was at
RA=60.2 deg, DECL=+24.8 deg. During the 1968-1969 session, Sekanina determined
the duration as May 22-July 4. The date of the nodal passage was then given as
June 12.2 (Solar Longitude=80.8 deg), while the average radiant position was
determined to be RA=63.3 deg, DECL=+27.1 deg.
Two radar studies were conducted using equipment at the University of
Adelaide (South Australia) during the 1960's. Unfortunately they were operated
over periods of about a week, so that their results might be considered somewhat
misleading when considering the radiant position and orbit. The first operated
in 1961, when C. S. Nilsson detected the Zeta Perseids during June 13-16, and
determined the radiant as RA=64.2 deg, DECL=+25.4 deg. He mentioned that the
equipment had also been operated during May 19-28, and that a radiant at RA=44.3
deg, DECL=+19.5 deg was probably the same as the June shower. The second survey
was conducted during June 9-14, 1969 by G. Gartrell and W. G. Elford. It
revealed a radiant at RA=65 deg, DECL=+27 deg, and the authors showed that the
stream was probably the twin of the Southern Taurids of November.
From observations made in the United States and Australia during 1971, it
appears that meteors from this shower can be visually detected coming up from
the horizon during the hours immediately after sunset and immediately before
sunrise. Daryl Skelsey (Sydney, Australia) observed 1 Zeta Perseid during 2
hours on June 5/6, while Karl Simmons estimated that the combined rates of the
Zeta Perseids and Arietids
reached 1 to 2 meteors per hour on the morning of June 6/7.