The duration of this daylight stream extends over the period of May 4-27.
The probable date of maximum activity falls on May 12 (Solar Longitude=51 deg),
at which time the radiant is at RA=13 deg, DECL=+22 deg. The maximum hourly rate
is near 8, while the radiant diameter is about 3 deg.
History
This daylight stream seems to have first been detected by observers at
Jodrell Bank (England), as J. A. Clegg, V. A. Hughes and Professor Alfred
Charles Bernard Lovell listed a radiant of RA=7 deg, DECL=+20 deg that was
detected on May 4, 1947. Although the radar was operated during May 1 to 30, no
additional activity from this stream was noted.
The Jodrell Bank equipment again detected this stream on May 12, 1955 (Solar
Longitude=50.8 deg). T. W. Davidson found 33 meteors which indicated a radiant
of RA=12 deg, DECL=+24 deg and a radiant diameter of 3 deg. The hourly rate was
given as 8. The radiant was called the "Upsilon Piscids," and Davidson noted it
was near a radiant detected at Jodrell Bank in 1951.
The next radar survey to detect this stream was conducted by B. L.
Kashcheyev and V. N. Lebedinets (Kharkov Polytechnical Institute, USSR) in 1960.
During the period of May 4-27, 17 meteors were observed. The date of the nodal
passage was given as May 12 (Solar Longitude=52 deg), at which time the radiant
was at RA=17 deg, DECL=+19 deg.
The last radio meteor survey to detect the May Piscids was the 1968-1969
session of the Radio Meteor Project. Zdenek Sekanina noted that activity was
detected during May 7-9, from an average radiant of RA=11.9 deg, DECL=+19.0 deg.
The date of the nodal passage was given as May 8.4 (Solar Longitude=47.3 deg).
The equipment was shut down during May 10-18, so that any extension in the
duration of the shower would have been missed.