First recognition of a possible December radiant near Delta
Arietis was made by Richard E. McCrosky and Annette Posen in
1959, while analyzing the photographic meteor orbits obtained by
the Harvard Meteor Project during 1952-1954. Seven meteors
indicated a shower was active during December 8-13, with a
probable maximum on the 8th. The average radiant was given as
RA=51 deg, DEC=+21 deg. In 1971, a computerized stream search of
the same 1952-1954 photographic meteors by Bertil-Anders
Lindblad, revealed the Delta Arietids to be split into northern
and southern branches; however, among the 14 meteors, which
suggested a duration of December 8-January 2, only 2 were from
the southern branch. The average radiant of the northern branch
was RA=54 deg, DEC=+25 deg.
No trace of this stream seems to be present in records covering the 19th century, but the first appearance of shower members may have occurred early in the 20th century, when several fireballs appear in various sources. The first really good visual radiants from this stream appear in Cuno Hoffmeister's Meteorstrome during 1912 and 1932. The most detailed observation obtained thus far was by observers in Waltair, India, on December 8, 1964. M. Srirama Rao, P. V. S. Rama Rao and P. Ramesh plotted 10 meteors from RA=57 deg, DEC=+22 deg and concluded that the radiant produced a rate of 7.5 meteors per hour. However, numerous observers' attempts to observe the shower during the 1970's and 1980's have never shown hourly rates greater than one at the time of the predicted maximum.
The orbits of the northern and southern branches as determined from 12 meteors and 3 meteors, respectively, are as follows:
AOP | AN | i | q | e | a |
|
---|---|---|---|---|---|---|
N. | 226.6 | 262.8 | 3.3 | 0.865 | 0.635 | 2.370 |
S. | 53.2 | 80.2 | 5.2 | 0.828 | 0.666 | 2.479 |
Original material by Gary
W. Kronk. Copyright ©1988, 1995
Original graphics by Eric
S. Young. Copyright ©1995