Alpha Aurigids

Observing

This shower's duration seems to persist from August 25 to September 6. Maximum occurs from α=85°, δ=+41° on September 1 (λ=158°). The annual maximum ZHR may be as high as 9, but outbursts of over 30 occurred in 1935 and 1986.

History

The Alpha Aurigids were discovered by C. Hoffmeister and A. Teichgraeber (Sonneberg, Germany) on the night of August 31/September 1, 1935 (λ=158°). The maximum hourly rate was reported as 30, while the radiant was determined as α=84.2°, δ=+42.0°. The meteors possessed an average magnitude of 2.62, while 74% of those brighter than magnitude 3.5 left trains. V. Guth immediately noted the similarity between this radiant and the predicted radiant of α=90.2°, δ=+39.3° for comet Kiess (1911 II).

In his 1948 book, Meteorströme, Hoffmeister noted that the link with comet Kiess made the circumstances of the 1935 observations curious. He pointed out that the comet's orbit was nearly parabolic, making the shower's sudden appearance 24 years after its perihelion passage difficult to explain. Hoffmeister examined his own annual observations made near the end of August and in early September, and noted probable detections of this shower in 1911, 1929, and 1930. In the former year, 5 of the 55 meteors he had plotted on September 2 (λ=159.2°) converged at α=84°, δ=+43°. During 1929, he found radiants of α=85 deg, δ=+38 deg on September 1 (λ=158.1°), α=87°, δ=+38° on September 3 (λ=159.8°), and α=89°, δ=+39° on September 4 (λ=161.0°). In 1930, one radiant was found at α=82°, δ=+38° on August 31 (λ=156.4°). Hoffmeister concluded that, although activity seems to have been present since the comet's perihelion passage, there is no evidence that the Alpha Aurigids are a permanent shower. He added that the strong 1935 shower was probably due to an isolated meteor group in the comet's orbit. Hoffmeister's conclusion seemed well founded, as additional observations failed to appear in the records of American, European, or Russian observers in the four decades following 1935, however, three significant observations have been made in recent years.

During 1979 and 1980 members of the Western Australia Meteor Section (WAMS) succeeded in observing the Alpha Aurigids. In the former year, observations were made over the period of August 25-September 2. Maximum activity came on September 2, when the ZHR reached 8.52+/-1.87 from a radiant of α=87 deg, δ=+42 deg. In 1980, observations were made during August 31-September 6. Maximum came on the 6th, when the ZHR reached 9.11+/-0.96, from α=82°, δ=+38°.

The latest detection of this shower came on September 1, 1986, when I. Tepliczky (Hungary) observed 24 meteors from RA=94°, DECL=+36.4° between 00:47 and 02:11 (UT). Around 01:25 (λ=158.34°), the ZHR reached 39.6+/-8.1. The meteors ranged in brightness from magnitude -4 to +4, with an average of +0.5.