Omicron Cetids

Observing

This meteor shower occurs exclusively during daylight hours during the period May 7 to June 9. Maximum may occur during the period of May 14 to 25, with a maximum hourly radio-echo rate of 18. The average position of the radiant near maximum is α=28°, δ=-3°. The meteor shower seems to occur annually, but may be prone to periodic or irregular increases in activity.

History

The Omicron Cetids were first detected on May 14, 1950, when A. Aspinall and Gerald S. Hawkins of Jodrell Bank radio observatory detected meteors at a rate of 18 per hour coming from RA=27.5°, DECL=-3.5°. Despite a 24-hour-a-day operation, this stream was again detected only on May 16 (RA=28.5°, DECL=+0.0°), 21 (RA=29.5°, DECL=-5.0°) and 23 (RA=34.0°, DECL=+1.0°), with hourly rates ranging from 18 to 22 per hour. The radiant diameter was less than 3° on each day, except for the 21st, when it was estimated as 10 deg across.

The Omicron Cetids were again detected at Jodrell Bank observers during May 14 to 17, 1951 (activity levels of 18 to 25 per hour), but were missed during 1952. Since the stream had generally produced activity levels greater than those observed for the Eta Aquarids, this prompted Mary Almond, K. Bullough and Hawkins to conclude that if the stream was present it "must have been less active than in 1950 or 1951."

The stream was possibly observed again at Jodrell Bank on May 17, 1953. Bullough gave the radiant as RA=11°, DECL=-2° and the hourly rate as 8. The radiant was less than 3° across. No further observations were made at this radio observatory during the period 1954 to 1958.

The next observation of this stream was made during 1961, by radio equipment at Adelaide Observatory in Australia. C. S. Nilsson noted three Omicron Cetids during the period of May 23-28, from an average radiant of RA=35.5°, DECL=+1.0°.

The true extent of this stream was finally realized during the two sessions of the Radio Meteor Project conducted during the 1960's by Zdenek Sekanina at Havana, Illinois. During 1962-1965, 11 meteors were detected during May 19-June 9, from an average radiant of RA=20.6°, DECL=+1.2°. The probable date of maximum was given as May 27.9. During 1969, 11 meteors were detected during the period of May 7-21, with the average radiant being RA=21.5°, DECL=-4.0°. The probable date of maximum was then given as May 9.0.