January Boötids |
|
This fairly short duration shower reaches maximum around
January 16-18 (J2000 solar longitude=295-297 deg), from an
average radiant of RA=226 deg, DECL=+44 deg. Meteors from this
stream are generally observable during January 9-18.
- The discovery of this meteor shower seems to have
occurred during the 1870's. According to an analysis by
William F. Denning, the Italian Meteoric Association
plotted 7 meteors from an average radiant of RA=221 deg,
DECL=+43 deg during January 1-15, 1872. On January 9,
1877, Denning himself plotted 6 meteors from RA=221 deg,
DECL=+42 deg.
- The next apparent sighting of this shower came on January
10, 1937 (Solar Longitude=288.9 deg), when A.
Teichgraeber noted a radiant at RA=225 deg, DECL=+45 deg.
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 deg, DECL=+43.9 deg 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, Dr. C. D. Watkins and Doylerush, detected a
shower from a radiant roughly given as RA=225 deg,
DECL=+25 deg; 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 deg, DECL=+37 deg. Maximum was
stated to have occurred on January 17 (Solar
Longitude=297 deg), 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 (Solar Longitude=297.6 deg). The hourly
rate reached 9, while the radiant appeared only 5 deg
across. The radiant was determined to be RA=237 deg,
DECL=+34 deg. 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 deg, DECL=+44.2 deg.
The average geocentric velocity was determined as 29.4
km/s.
- The strongest evidence for the existence of this
short-duration meteor shower was obtained by Zdenek
Sekanina in 1969, during the second session of the Radio
Meteor Project. The orbit was based on 15 meteors and is
remarkably similar to the Aten class of asteroids, or
bodies with semimajor axes less than 1 AU. At the same
time the short duration of the shower might indicate the
stream is fairly young, so that the parent object may
still be moving in this or a similar orbit.
|
January Boötids |
Argument of Perihelion () [J2000] |
346.4 deg. |
Ascending Node ()
[J2000] |
294.9 deg. |
Inclination (i) [J2000] |
59.9 deg. |
Perihelion Distance (q) |
0.836 AU |
Eccentricity (e) |
0.090 |
Semimajor axis (a) |
0.919 AU |
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