Eta Lyrids

Observing

This meteor shower occurs during the period May 3 to 12. The maximum is uncertain, but probably occurs within the period of May 8 to 10, with an hourly rate of 1 to 4. The average position of the radiant near maximum is α=292°, δ=+40°.

History

This is a rather poorly observed stream, but it is interesting because of its potential relationship to a comet seen in 1983. The discovery was basically predicted on 1983 May 9, when an alert as to potential meteor activity from comet IRAS-Araki-Alcock was announced by Jack Drummond (Stewart Observatory) on IAU Circular 3801. Drummond predicted a likely shower would occur on May 10.1 (solar longitude 49.1°) from a radiant of RA=289°, DEC=+44°. IAU Circular 3811 announced that a radio meteor survey in Ottawa that ran for a 72-hour period centered on May 10.08, revealed no evidence of enhanced meteor activity. In addition, a visual and photographic search by S. Clifton (Marshall Space Flight Center) during May 10.0 to 10.4 revealed no trace of the predicted activity. Interestingly, Drummond announced the results of his observations on IAU Circular 3817 (1983 June 1). He said his visual observations revealed definite activity from the predicted radiant during the period of May 9.47 to 11.44. The rates were corrected to Zenithal Hourly Rates (ZHR). His highest rate of ZHR=5.1 occured at the beginning of the period on May 9.47, while his second highest rate of ZHR=4.1 occurred during his next period of observation on May 10.32. Rates during the remainder of the period ranged from ZHR=2.4-3.2.

Although a few meteor observers had gotten word of a possible meteor shower from IAU Circular 3801, Japanese observers realized the potential for a meteor shower a bit earlier and were able to alert several observers in Japan. Their successful observations were reported in the June 1984 issue of the Belgian publication Werkgroepnieuws. Observations spanned the period of May 7.7 to 14.6, although no meteors were noted from this radiant from May 12 onward. They converted their observations to ZHRs and obtained their highest rates of 3.0 on May 10.7, 2.9 on May 7.7, and 2.8 on May 11.6. Several radiants were determined from the available data and they are given as follow:

DateRadiantObserver
1983 May 7.56266, +37Kawasaki
1983 May 7.77276, +35Ueda
1983 May 8.71259, +40Mameta
1983 May 9.57270, +40Kawasaki
1983 May 9.69280, +35Tomioka
1983 May 10.57274, +39Kawasaki
1983 May 10.58270, +45Mameta
1983 May 10.72282, +40Tomioka
1983 May 11.61262, +46Fukui

Among visual records of the past, there is some indication that this radiant was occasionally seen. Although experienced observers like W. F. Denning and A. King never listed observations of this radiant in their papers, Denning did mention in his 1899 catalog that a radiant was seen by H. Corder on 1895 May 1-4. The radiant was given as α=278°, δ=+43°. No further radiants exist in the literature until C. Hoffmeister published his book Meteorströme in 1948. In that book radiants were reported in 1910, 1929, and 1930 as follows:

DateRadiantObserver
1910 May 4282, +45C. Hoffmeister
1929 May 6.44279, +38C. Hoffmeister
1930 May 1.44284, +44C. Hoffmeister

More evidence pointing to the past existence of this meteor stream comes from the records of the American Meteor Society, where similar radiants were reported in 1942 and 1953. Although some of the radiants reported by Paul Anderson may not belong, they are nevertheless an interesting indication that that region was particularly active in 1942.

DateRadiantObserver
1942 May 7.2303, +38P. Anderson
1942 May 8.3293, +42P. Anderson
1942 May 10.3294, +45P. Anderson
1942 May 10.3295, +36P. Anderson
1953 May 10.2276, +45C. Worley

For the most part, the Eta Lyrids have been ignored ever since 1983, except for a few observers who occasionally note activity of 1 or 2 an hour from this radiant while they are observing the more active Eta Aquarid radiant. Interestingly, during 2000, several observers reported activity that reached hourly rates of 2 to 6.