This stream appears to have been discovered during 1957 and 1958, while radio-echo surveys were being conducted at Adelaide Observatory in South Australia. A. A. Weiss reported the shower to have suddenly appeared with rates of 30 per hour from a compact radiant. The radiant’s position was determined as RA=307°, DECL=-35° in 1957, and RA=301°, DECL=-36° in 1958. Weiss said no hint of the shower had been noted in 1952, 1953, 1954 and 1956, and that the 1957-1958 appearance was near “the limit of resolution of the equipment.” The date of maximum was given as June 11, while the total duration was given as five days.
More sensitive radar equipment was operated by G. Gartrell and W. G. Elford at Adelaide, South Australia, during 1968-1969. Only 4 meteors were detected, so that the stream seemed practically nonexistent. For the mean activity date of June 10, the radiant was established as RA=297°, DECL=-34°.
Visual activity from this shower seems rare, as some of the most comprehensive southern hemisphere radiant catalogs (including C. Hoffmiester’s “Meteorströme” in 1948) have failed to reveal convincing evidence of the radiant’s existence prior to 1957. Recent observations also appear to be rare, although Jeff Wood, director of the meteor section of the National Association of Planetary Observers (Australia), lists what appears to be a probable detection of this shower among the 1980 observations of the Western Australia Meteor Section. The radiant was called the “Alpha Microscopiids” and was detected only during June 11 and 12. A maximum ZHR of 1.43±0.13 occurred on June 11 from a radiant of RA=305°, DECL=-36°. The BMS Radiant Catalogue lists this shower as occurring during June 8-16, with a maximum ZHR of 4, and an average radiant of RA=304°, DECL=-35°.