Aurigids

Observing

There has been some question as to the continued existence of this meteor radiant and the question can only be resolved by observations from experienced observers. In general, observations have been made between January 31 and February 23, with a maximum of about 2 meteors per hour occurring during February 5-10. The radiant is normally located at α=74°, δ=+42°, although this must be a rough estimate as precise radiant positions, especially in recent decades, have been rare. The meteors are slow. Although the average magnitude is between 3 and 5, the shower is known for bright fireballs. The radiant's daily motion is about +0.7° in α and +0.3° in δ.

History

The discovery of the Aurigids should be credited to Robert P. Greg (Manchester, England), who, during 1845 to 1863, managed to plot 13 meteors from a radiant of RA=76°, DECL=+40° that seemed active between February 9 and 17. On 1868 February 18, G. Zezioli (Bergamo, Italy) noticed 18 meteors from a radiant near Capella. G. V. Schiaparelli derived a radiant of RA=74°, DECL=+48° from those observations.

W. F. Denning (Bristol, England) pointed out on several occasions that a meteor shower with a radiant just 5° south-southwest of Alpha Aurigae was active during February. He considered the shower's duration to be from the 7th to the 23rd, and gave a radiant derived from his own observations as RA=75 deg, DECL=+41 deg. He said, "It often furnishes bright meteors in the evenings...." During 1912, he further elaborated on his Aurigid observations, saying that his radiant of RA=75°, DECL=+41°, was derived from 7 bright meteors plotted between 1876 and 1903. The meteors were described as slow and left trains.

Some of the most notable Aurigid fireballs of this century follow:

Aurigid Fireballs

Date (UT)α°δ°MagnitudeSource
1901, Feb. 13.972+43"brilliant"MNRAS, 72, 426
1910, Feb. 17.872+43-5MNRAS, 72, 426
1920, Feb. 17.972+43---Obs., 43, 166
1935, Feb. 27.880+46-5FOR, No. 60
1970, Jan. 31.462.1+37.6-9.1CAPS, No. 665

The first visual study of this shower was conducted during 1962 and 1967, by a group led by V. Znojil (Public Observatory, Brno, Czechoslovakia). In 1962, observations were made from Mt. Klet on February 7/8 and 10/11. Two groups of observers applied different observing methods: one used no optical aid and observed with a limiting magnitude of 6.0, while the other group used 8-cm binoculars, which gave a limiting magnitude of 10.8. The naked-eye observers detected hourly rates of 1.5+/-0.5 on the 7/8 and 1.1+/-0.4 on the 10/11. The average meteor magnitude was noted as 2.9 on the first date and 4.9 on the second. The binocular observations revealed 11 members, with the average Aurigid magnitude being 9.0. During 1967, observations were made from Brno on February 4/5, 6/7, 8/9 and 10/11. Only binoculars were used. The results were that 7 Aurigids were detected and the average magnitude was 8.3.

Znojil's analysis of the Aurigid observations of 1962 and 1967, primarily discussed the apparent lack of small particles within the stream. He pointed out that the ratio of Aurigid meteors to sporadics changed markedly between visual and binocular observations, yet the change was always consistent. For instance, visual observations on 1962 February 7/8, revealed 21 Aurigids and 127 sporadics, and the February 10/11 visual observations revealed 24 Aurigids and 131 sporadics. On the other hand, binocular observations made on 2 days in 1962, revealed 11 Aurigids and 279 sporadics, while for the 4 days in 1967, they revealed 7 Aurigids and 234 sporadics. Znojil concluded that the small particles of this stream came about as a result of "fragmentation and cosmic erosion." He added that there was a possibility that the small particles were coming from a radiant that "is slightly displaced from the normally given position...."

Recent observations have not been numerous. During 1970 February 8 to 14, Bill Gates (Albuquerque, New Mexico) acquired 11 counts which revealed hourly rates of only 0.6, while Martin Hale (New York) and Rick Hill (North Carolina) obtained 33 counts during 1972 February 5 to 17, which revealed an hourly rate of only 0.2. Gates described the meteors as being "very slow" and generally yellow. He also specifically pointed out the very low activity in the early seventies. In contrast to these low hourly rates, the Western Australia Meteor Section obtained a ZHR of 7.32+/-1.07 during 1980 February 2-7. The date of maximum was given as February 4, while the radiant was α=79 deg, δ=+39 deg.