History
The visual support for this shower is extremely weak, but it seems possible that W. F. Denning (Bristol, England) plotted 21 meteors from a radiant of RA=284°, DEC=+57° during July 16-18, 1876. He described the meteors as very rapid and faint. Thereafter, only three doubly observed meteors of magnitude 1-2 appear to be related to Denning’s radiant. These were reported by English observers in 1908 and 1914.
The shower’s official discovery should be attributed to Allan F. Cook, B.-A. Lindblad, B. G. Marsden, R. E. McCrosky and A. Posen, who isolated three photographic meteors detected during the Harvard Meteor Project of 1952-1954. The duration was given as July 6-24, while the average radiant was RA=271°, DEC=+59°. Only a parabolic orbit was given.
| ω | Ω | i | q | e | a |
|---|---|---|---|---|---|
| 190 | 113 | 43 | 1.01 | 1.0 | — |
Although the evidence was not considered strong, the authors noted that the orbit they had determined bore a strong resemblance to that of comet Metcalf (1919 V).
| ω | Ω | i | q | e | a |
|---|---|---|---|---|---|
| 185.7 | 121.4 | 46.4 | 1.115 | 1.0 | — |
Official confirmation of this stream’s existence came in 1976 as Zdenek Sekanina published his analysis of the data acquired during the 1968-1969 session of the Radio Meteor Project . He found the Omicron Draconids to possess a duration extending over the period of July 14-28. The date of the nodal passage was given as July 17.7 (solar longitude=114.7 deg), at which time the radiant was at RA=284.7 deg, DEC=+60.9 deg. The following orbit being revealed.
| ω | Ω | i | q | e | a |
|---|---|---|---|---|---|
| 192.2 | 114.7 | 46.2 | 1.006 | 0.768 | 4.329 |
No additional observations seem to have been made, as the extensive records of the American Meteor Society, as well as the more than 5000 visual radiants given in C. Hoffmeister’s book Meteorströme, fail to reveal a trace.