[Prev][Next][Index][Thread]
(meteorobs) A-T campaign 96: Part 2
Part 2: Search for Historical Data
By Gary W. Kronk
Following the apparent independent discovery of activity in the region of
Aries and Triangulum, Gary W. Kronk began trying to find signs that the
stream had been detected in the past. The most obvious records to check
were several lists of radiants published during the 19th and early 20th
centuries. Papers by Alphonso King, Alexander S. Herschel, Eduard Heis, and
Robert P. Greg revealed no trace of the Aries-Triangulum activity, but the
1899 catalog of William F. Denning did reveal something interesting.
Denning included a radiant called the Beta Triangulids, which he observed
during the period of August 24 to September 14, 1872, from a radiant of
RA=34 degrees, DEC=+35 degrees. Denning's supplement to that catalog was
published in 1912 and included a radiant detected during September 3-17,
1885, from RA=29 degrees, DEC=+36 degrees, and a radiant detected during
September 3-7, 1902, from RA=30 degrees, DEC=+37 degrees. For the most
part, these radiants were typically higher in declination than that seen in
1993, and they were certainly of a greater duration. It should even be
noted that Denning's 1902 radiant was the only radiant to average more than
one meteor per night, which indicated the overall weakness of this data.
Kronk decided the evidence from Denning was too weak to be considered a
possible confirmation.
Kronk's next area to search was a list of over 7000 visual radiants he had
compiled from articles written during the period of 1934 to 1967 by
long-time American Meteor Society director Charles Olivier. Interestingly,
Kronk compiled the following list from that data.
Desig. Date RA DEC Long Observer
1683a 1934, Sep. 10.0 34.0 +31.0 166.6 Smith, Franklin W.
1683b 1934, Sep. 11.0 33.0 +27.0 167.6 Smith, Franklin W.
4051 1940, Sep. 8.0 26.0 +19.0 165.2 Khan, Mohd. A. R.
3058 1940, Sep. 12.3 36.0 +20.0 169.4 Anderson, Paul
4592 1945, Sep. 9.7 32.0 +26.0 166.6 Komaki, Koziro
3111 1950, Sep. 6.2 30.0 +23.0 163.0 Worley, Charles E.
3110 1950, Sep. 7.2* 27.5 +21.0 164.0 Worley, Charles E.
3186 1951, Sep. 9.3 26.0 +32.5 165.8 Knowles, Jeremy H.
3192 1951, Sep. 10.8 26.0 +27.0 167.3 Knowles, Jeremy H.
3413 1951, Sep. 13.3 27.0 +24.0 169.7 Worley, Charles E.
3415 1951, Sep. 15.3 31.0 +23.5 171.6 Worley, Charles E.
3888 1955, Sep. 13.3 29.5 +20.0 169.7 Knowles, Jeremy H.
5507 1967, Sep. 11.8* 25.0 +29.0 168.3 Menzel, R.
*Means date was an average of two or more nights of observation.
Kronk next searched through another extensive list of radiants that had
been compiled by Cuno Hoffmeister in his 1948 book Meteorstrome. The
following radiants were extracted.
Desig. Date RA DEC Long Observer
747 1915, Sep. 12.9 35 +21 169 Hoffmeister
1075 1921, Sep. 9.0 34 +17 165.8 Hoffmeister
1240 1923, Sep. 12.7 25 +25 168.9 Hoffmeister
5086 1929, Sep. 9.6 33 +34 166.4 Richter
2273 1934, Sep. 10.0 23 +29 166.6 Hoffmeister
2716 1936, Sep. 10.5 37 +29 167.6 Hoffmeister
4141 1937, Sep. 7.0 32 +27 164.0 Hoffmeister
Several very notable occurrences became apparent when the AMS and
Hoffmiester lists were compared. First, on September 10, 1934 this radiant
was independently found by Smith in the United States and Hoffmeister in
Germany. Second, during 1940 United States observers Khan and Anderson
independently noted radiants from this region within four days of each
other. Thirdly, during 1951 United States obervers Knowles and Worley
independently determined a total of four radiants within a six day period.
One major question quickly arose concerning the data of the AMS and
Hoffmeister: How accurate were these radiants? First, Hoffmeister and the
AMS observers of 1934, 1940, and 1951 were all very prolific observers,
with the AMS observers being among the most prolific and experienced
observers in that organization's history. Second, although Kronk was unable
to uncover the criteria for Hoffmeister's list, he did note that during the
days of Charles Olivier the AMS criteria for radiant determination was the
intersection of four or more meteors within a circle of no more than 2.5
degrees, which is more stringent than what some groups accept today.
Taking all known visual observations of this radiant into consideration,it
should be noted that not only was this radiant independently found by two
experienced observers in 1993, but it was also independently found by two
experienced observers in 1934, 1940, and 1951. It also appeared that visual
activity had been confined within the period defined by solar longitudes of
163 to 172 degrees, which roughly equated to the period of September 6 to
15. Finally, the uncertainty as to the exact location of the radiant was
not decided by the newly uncovered historical data. In 1993, Kronk and
Sleeter found the radiant in Triangulum, while Gliba noted it was possibly
about 10 degrees south in Aries. The accounts of the AMS and Hoffmeister
seem to favor the existence of both radiants almost equally.
The next installment will be Part 3: An Orbit is Determined
(To be posted around September 3 or 4)