This ecliptic stream possesses a long duration extending from April 8 to
June 16. Maximum occurs during May 18-19 from an average radiant of RA=253 deg,
DECL=-15 deg. The maximum ZHR is about 2-3, while the radiant diameter is near 3
deg.
History
The first observation of this meteor shower was made by H. Corder during May
12-14, 1896. He had plotted five "slow" meteors from a radiant of RA=248 deg,
DECL=-15 deg.
During 1935 this shower experienced the beginning of recognition as an
annual shower when Ronald A. McIntosh listed it in his paper "An Index of
Southern Meteor Showers." Designated number 160 and called the "Phi Ophiuchids,"
this shower was given a duration of May 7-14, with the average radiant being
given as RA=248.5 deg, DECL=-15 deg.
The publication of Cuno Hoffmeister's Meteorströme during 1948 contained
even more support for the Northern May Ophiuchids. Hoffmeister noted a
collection of radiants which indicated a radiant of RA=250 deg, DECL=-18 deg
reaching maximum at a solar longitude of 54 deg (May 15). This radiant was based
on seven individual radiants determined by German observers during 1914 to 1937.
One of the radiants, designated number 693, was composed of 16 meteors whose
intersection indicated a radiant diameter of 3 deg.
The greatest amount of data to be accumulated on the Northern May Ophiuchids
came from the two sessions of the Radio Meteor Project. Zdenek Sekanina found a
duration extending from May 3 to June 4 during the 1961-1965 survey. The date of
the nodal passage was determined as May 17.6 (Solar Longitude=56.2 deg), at
which time the radiant position was RA=252.3 deg, DECL=-16.9 deg. During the
1968-1969 survey, Sekanina found a duration of April 8 to June 16. The nodal
passage was determined as May 19.0 (Solar Longitude=57.6 deg), at which time the
radiant was at RA=256.2 deg, DECL=-12.8 deg.
The Western Australia Meteor Section has obtained good observations of the
shower in recent years. According to the section's director, Jeff Wood,
observations conducted in 1979 revealed "Eta Ophiuchids" during May 16-27. A
maximum ZHR of 2.460.56 came on May 19, at which time the radiant was at RA=256
deg, DECL=-13 deg.