January Boötids

Observing

This fairly short duration shower reaches maximum around January 16-18 (λ=295-297°), from an average radiant of RA=226°, DECL=+44°. Meteors from this stream are generally observable during January 9-18.

History

The discovery of this meteor shower seems to have occurred during the 1870's. According to an analysis by W. F. Denning, the Italian Meteoric Association plotted 7 meteors from an average radiant of RA=221°, DECL=+43° during January 1-15, 1872. On January 9, 1877, Denning himself plotted 6 meteors from RA=221°, DECL=+42°.

The next apparent sighting of this shower came on January 10, 1937 (λ=288.9°), when A. Teichgraeber noted a radiant at RA=225°, DECL=+45°. This observation marked the only radiant listed in Cuno Hoffmeister's Meteorströme, which listed 5406 visual radiants. This radiant was designated 5061.

Photographic studies have not revealed many members of this stream, possibly due to a lack of cameras operating around mid-January. In fact, the only apparent representative of this stream was detected on January 13, 1953, by cameras of the Harvard Meteor Project. The meteor had a magnitude of 0.3 and possessed a radiant of RA=223.0°, DECL=+43.9° The geocentric velocity was 27.3 km/s, while the height at which the meteor first became visible was 95.0 km.

Radar studies have also detected this stream on three occasions. During January 16 to 19, 1957, Jodrell Bank observers, C. D. Watkins and Doylerush, detected a shower from a radiant roughly given as RA=225°, DECL=+25°; however, the large radiant diameter of 10 deg to 15 deg caused Jodrell Bank researchers to reevaluate the data and they subsequently arrived at an average radiant of RA=233°, DECL=+37°. Maximum was stated to have occurred on January 17 (λ=297°), when the hourly rate reached 25. There seemed to be evidence that the daily motion was roughly 2 deg eastward.

The stream was again detected at Jodrell Bank in 1958. On this occasion, however, radio meteors were only detected on January 18 (λ=297.6°). The hourly rate reached 9, while the radiant appeared only 5 deg across. The radiant was determined to be RA=237°, DECL=+34°. While analyzing all observations obtained during 1957 and 1958, G. C. Evans concluded that the January Boötids possessed a duration extending from solar longitude 290 deg to 304 deg, or roughly from January 11 to 25. Interestingly, during January 15-16, 1958, eight radar stations in the U.S.S.R. detected an unusual increase in meteoric activity. Although no radiant was determined, the activity seems to add some support to Jodrell Bank's 1958 observation at least in terms of enhanced activity.

The third detection of this stream using radar came during January 14 to 15, 1969, when the Radio Meteor Project at Havana, Illinois, detected 15 meteors from this stream. No apparent members were seen during January 13 or during January 16-17 and the radar had been shut down during January 1-12 and January 18-26. The average radiant was determined as RA=225.8°, DECL=+44.2°. The average geocentric velocity was determined as 29.4 km/s.